---
title: "Pentel Ain Stein Lead: Sizes, Grades and Strength"
canonical: "https://stationerytimes.com/guides/pentel-ain-stein-lead/"
description: "Pentel Ain Stein pencil lead explained: 0.2 to 0.9 mm tubes and lead counts, grades, the ceramic cell structure, strength claims and the newer Pentel Ain."
category: "Accessories"
type: "Pencil lead"
published: 2026-10-20
updated: 2026-10-20
author: "Ellis Penhale"
publisher: "Stationery Times"
sources: 15
products:
  - name: "Pentel Ain Stein mechanical pencil lead refill (C275, 0.5 mm, 40 leads)"
    brand: "Pentel"
    brand_origin: "Japan"
    made_in: "Not stated"
    material: "Graphite in a ceramic cell structure"
    price_band: "$ (under $5 per item, typical US retail, October 2026)"
    manufacturer: "ASTRUM Corporation (Tokyo), called Pentel Co., Ltd. until April 1, 2026; Pentel remains the brand"
    model: "Ain Stein"
    mpn: "C275"
---

# Pentel Ain Stein Lead: Sizes, Grades and Strength

> Pentel Ain Stein is a premium mechanical pencil lead that Pentel says uses a porous ceramic cell structure for strength. It comes in 60 mm leads from 0.2 to 0.9 mm; the 0.5 mm C275 tube holds 40 leads. In Japan, Pentel replaced it with the Pentel Ain brand in January 2023.

- URL: https://stationerytimes.com/guides/pentel-ain-stein-lead/
- Category: Accessories
- Author: Ellis Penhale
- Published: 2026-10-20
- Updated: 2026-10-20

![Pentel Ain Stein 0.5 mm lead refill: a clear tube with a dark blue swivel cap and three loose 60 mm (2.4 in) leads drawn to scale; inset: a lead's cross-section with graphite held in ceramic cells](https://stationerytimes.com/images/raster/pentel-ain-stein-lead-16x9.png)

*Leads drawn to scale at 60 mm; the tube is drawn by eye.* Original drawing (SVG): https://stationerytimes.com/images/pentel-ain-stein-lead-cover.svg. Drawings © 2026 Stationery Times, reusable with credit under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/).

## Product facts

| Product | Brand | Brand origin | Made in | Material | Released | Price range (typical US retail, October 2026) |
|---|---|---|---|---|---|---|
| Pentel Ain Stein mechanical pencil lead refill (C275, 0.5 mm, 40 leads) | Pentel (by ASTRUM Corporation (Tokyo), called Pentel Co., Ltd. until April 1, 2026; Pentel remains the brand) | Japan | Not stated | Graphite in a ceramic cell structure | – | $: under $5 per item |

- Made in (Pentel Ain Stein mechanical pencil lead refill (C275, 0.5 mm, 40 leads)): Not stated. None of the listings we read (Monk, Doublet, Cult Pens, Markers n Pens, Amazon) state where Ain Stein leads are made. Pentel's Japanese site no longer lists Ain Stein, and Pentel of America's 2022 and 2023 product catalogs, which give an origin for each product, don't include it. Pentel is a Japanese company, but that doesn't tell us the factory.

## Key takeaways

- The 0.5 mm refill (C275) holds 40 leads; the 0.3 mm C273 holds 15, the 0.7 mm C277 40 and the 0.9 mm C279 36.
- Retailers list Ain Stein leads at 60 mm (2.4 in) long, in plastic swivel-top tubes.
- Retailers describe a ceramic frame that holds the graphite from inside; Monk says it is 30% stronger than the competitive average, Cult Pens about 10% stronger than Pentel's earlier leads.
- Pentel launched the Pentel Ain brand in Japan on January 30, 2023, its first lead brand renewal in 13 years, at ¥220 (about US$1.40) a tube.
- A tube sells in our $ band (under $5) in the US.

## What is Pentel Ain Stein lead?

**It's Pentel's premium refill lead for mechanical pencils, built for strength.** Retailers describe a ceramic cell structure, a frame that holds the graphite together from the inside while keeping it dark and smooth. Monk and Doublet add that the tube contains at least 92% recycled material.

Its closest premium rival is [uni Nano Dia](https://stationerytimes.com/guides/uni-nano-dia-lead/). Pentel no longer lists Ain Stein on its Japanese site, where the newer Pentel Ain has taken its place, and Pentel of America's 2023 product guide lists only its Hi-Polymer leads.

## Pentel Ain Stein sizes and lead counts

**Every size uses 60 mm (2.4 in) leads; how many fit in a tube depends on the diameter.**

| Size | Code | Leads per tube | Grades listed |
|---|---|---|---|
| 0.2 mm | Not found | 20 | B and others |
| 0.3 mm | C273 | 15 | H, HB, B, 2B |
| 0.5 mm | C275 | 40 | 2H to 4B |
| 0.7 mm | C277 | 40 | H, HB, B, 2B |
| 0.9 mm | C279 | 36 | HB, B, 2B |

Counts and grades come from retailer listings (Monk, Doublet, Amazon, Markers n Pens, eBay); the 0.2 mm count is from a German Kaufland listing we couldn't reopen. Availability by grade varies by country, so check the exact listing before you order an unusual grade.

![Pentel Ain Stein lead cross-sections to scale: 0.2 mm (20 leads), 0.3 mm C273 (15), 0.5 mm C275 (40), 0.7 mm C277 (40) and 0.9 mm C279 (36), all 60 mm long](https://stationerytimes.com/images/pentel-ain-stein-lead-sizes.svg)

*Thicker leads, fewer per tube (lead counts per retailers).*

## Which size should you buy?

**Buy the size printed on your pencil; lead only fits the diameter it was made for.** Most everyday pencils, including the [Pentel Sharp P205](https://stationerytimes.com/guides/pentel-sharp-p205/) and [uni Kuru Toga](https://stationerytimes.com/guides/uni-kuru-toga/), take 0.5 mm.

Use 0.3 mm for small handwriting and fine technical lines, and 0.7 or 0.9 mm if you press hard or sketch. The 0.2 mm tube is for 0.2 mm pencils such as the [Pentel Orenz](https://stationerytimes.com/guides/pentel-orenz/).

## Which grade should you choose?

**Start with HB for writing, and go to B or 2B if you want darker, smoother lines.** Softer grades are darker but wear faster and smudge more; harder H grades stay sharp and light, which suits drafting.


## Is Ain Stein really stronger?

**Retailers say it is, but there's no independent figure.** Monk, a Canadian retailer, quotes 30% stronger than the competitive average, and Cult Pens says about 10% stronger than Pentel's original refill leads.

Strength is the point of the ceramic frame. In a fine size like 0.3 mm, fewer breaks matter more than in 0.7 mm, which is already sturdy.

## What happened to Ain Stein in Japan?

**In January 2023, Pentel replaced it in Japan with a new lead brand, Pentel Ain.** Impress Watch reported that Pentel called it its first lead brand renewal in 13 years, on sale from January 30, 2023, at ¥220 (about US$1.40) a tube.

Pentel's Japanese site says Ain uses a new process with a special oil, so graphite and resin carbide break down smoothly as you write. It comes in seven sizes from 0.2 to 1.3 mm, with 2B, B and HB in every size, and tube counts of 20 (0.2 mm), 25 (0.3 mm), 30 (0.4 mm) and 40 (0.5 mm). US and European shops still sell Ain Stein, and The Online Pen Company calls Ain the new version of the discontinued Ain Stein.

## How does it compare with other Pentel lead?

**Ain Stein is the premium line; Super Hi-Polymer is Pentel's everyday lead.**

| | Ain Stein | Super Hi-Polymer | Pentel Ain |
|---|---|---|---|
| Position | Premium, ceramic cell frame | Everyday | Ain Stein's successor in Japan |
| 0.5 mm tube | 40 leads (C275) | 12 or 30 leads (C505, C25) in the US | 40 leads |
| Launched | About 2010 | Not checked | January 30, 2023 (Japan) |

The "about 2010" date comes from Impress Watch's note that Ain was Pentel's first new lead brand in 13 years. A good drafting pencil to pair it with is the [Pentel Graph 1000 for Pro](https://stationerytimes.com/guides/pentel-graph-1000-for-pro/).

## Where is Pentel Ain Stein made?

**None of the listings we found say where it is made.** Pentel's Japanese site no longer lists Ain Stein, and Pentel of America's recent catalogs, which give an origin for each product, don't include it. Pentel's maker, renamed ASTRUM Corporation on April 1, 2026, is based in Tokyo, but that doesn't tell us the factory, so we list it as not stated.

## Frequently asked questions

### How many leads are in a Pentel Ain Stein tube?

It depends on the size: 40 leads in 0.5 mm (C275) and 0.7 mm (C277), 36 in 0.9 mm (C279), 15 in 0.3 mm (C273) and 20 in 0.2 mm, per retailer listings.

### How long are Pentel Ain Stein leads?

Retailers list them at 60 mm (2.4 in), the usual length for mechanical pencil lead, so they fit standard pencils of the matching diameter.

### Is Pentel Ain Stein discontinued?

In Japan, Pentel replaced it with a new lead brand, Pentel Ain, from January 30, 2023. Ain Stein tubes are still sold by many US and European retailers, which call Ain its successor.

### Is Ain Stein stronger than regular lead?

Retailers say so: Monk, a Canadian retailer, quotes 30% stronger than the competitive average, and Cult Pens about 10% stronger than Pentel's original leads. We haven't tested it, and no independent figure was available.

### What grades does Ain Stein come in?

HB, B and 2B are the most widely stocked. Listings for 0.5 mm also show 2H, H, 3B and 4B, while 0.7 mm is listed in H, HB, B and 2B.

### What is the difference between Pentel Ain Stein and Super Hi-Polymer?

Super Hi-Polymer is Pentel's everyday lead, often sold in multi-tube packs. Ain Stein is the premium line with the ceramic cell structure.

### Where is Pentel Ain Stein lead made?

The listings we found don't say, and Pentel's current Japanese and US materials don't cover Ain Stein. Pentel's maker, ASTRUM Corporation, is based in Tokyo, Japan.

## Sources

- [Pentel Ain | ぺんてる (Pentel Japan: Ain lead, special-oil process, 0.2 to 1.3 mm, 20 to 40 leads per tube)](https://www.pentel.co.jp/products/mechanicalpencil/lead_pentel_ain/)
- [企業情報 | アストラム株式会社 (ASTRUM company profile, Japanese: renamed from Pentel Co., Ltd. on April 1, 2026; Pentel stays the brand)](https://www.astrum-st.com/company/)
- [Monk Office: Pentel Ain Stein leads HB 0.5 mm, 40 leads (C275HB; 30% stronger claim, recycled content)](https://commercial.monk.ca/office-products/drafting-supplies/pencil-leads/penc275hb-ain-stein-leads-hb-05mm-40pk)
- [Doublet Smart Supplies: Pentel C275 Ain Stein 0.5 mm B, tube of 40](https://smartsupplies.doublet.com.au/product/pentel-c275-ain-stein-mechanical-pencil-lead-refill-05mm-b-red-tube-40/7110807)
- [Doublet Smart Supplies: Pentel C275 Ain Stein 0.5 mm HB, dark blue tube of 40](https://smartsupplies.doublet.com.au/product/pentel-c275-ain-stein-mechanical-pencil-lead-refill-05mm-hb-dark-blue-tube-40/7110809)
- [Doublet Smart Supplies: Pentel C273 Ain Stein 0.3 mm, tube of 15 (92% recycled material)](https://smartsupplies.doublet.com.au/product/pentel-c273-ain-stein-mechanical-pencil-lead-refill-03mm-hb-grey-tube-15/7110803)
- [Doublet Smart Supplies: Pentel C279 Ain Stein 0.9 mm 2B, 60 mm, tube of 36](https://smartsupplies.doublet.com.au/product/pentel-c279-ain-stein-mechanical-pencil-lead-refill-09mm-2b-black-tube-36/7110818)
- [Amazon: Pentel 0.9 mm B Ain Stein refill lead (36 leads per tube)](https://www.amazon.com/Pentel-Stein-Refill-Tubes-Leads/dp/B00CN3M7OE)
- [Markers n Pens: Pentel Ain Stein refill leads 0.7 mm (40 leads; 2B, B, HB, H)](https://markersnpens.com/products/pentel-ain-stein-refill-leads-0-7-mm)
- [Kaufland.de: Pentel Ain Stein refill leads (German listings, including 0.2 mm B, 20 leads, 60 mm, and 0.9 mm HB)](https://www.kaufland.de/product/313697718/)
- [Cult Pens: Pentel Ain Stein lead (ceramic frame, about 10% stronger than Pentel's original leads, swivel-top tubes)](https://cultpens.com/collections/pentel-ain-stein-lead)
- [eBay: Pentel Ain Stein leads 0.3 to 0.9 mm (grades by size)](https://www.ebay.com/itm/323424862823)
- [ぺんてる、シャープペン替芯新ブランド「Pentel Ain」 (Impress Watch, Japanese: on sale January 30, 2023, ¥220, first renewal in 13 years, seven sizes)](https://www.watch.impress.co.jp/docs/news/1469039.html)
- [The Online Pen Company: Pentel Ain lead refill (new version of the discontinued Ain Stein)](https://www.theonlinepencompany.com/us/pentel-ain-lead-refill)
- [Pentel of America: 2023 to 2024 Product Guide (US lead refills; no Ain Stein)](https://pentel.mywestamerica.com/2023ProductGuide/2/)