--- title: "Seed Radar Eraser: Japan's Blue-Sleeve Plastic Eraser" canonical: "https://stationerytimes.com/guides/seed-radar-eraser/" description: "Seed Radar eraser explained: the SR-100's 55 × 21 × 12 mm size, five sizes and Japan prices, the 97% erasing test, the crumb-catching Matoma Radar, and origin." category: "Accessories" type: "Eraser" published: 2026-10-22 updated: 2026-10-22 author: "Ellis Penhale" publisher: "Stationery Times" sources: 6 products: - name: "Seed Radar plastic eraser, SR-100 (EP-SR-100)" brand: "Seed" brand_origin: "Japan" made_in: "Not stated" material: "Plastic (PVC) eraser, phthalate-free; paper sleeve (Seed)" released: "1968" price_band: "$ (under $5 per item, typical US retail, October 2026)" manufacturer: "Seed Co., Ltd. (Toyonaka, Osaka)" model: "Radar SR-100" mpn: "EP-SR-100" gtin: "4906643015097" url: "https://www.seedr.co.jp/products/radar-sr/" --- # Seed Radar Eraser: Japan's Blue-Sleeve Plastic Eraser > The Seed Radar is a white plastic eraser in a blue sleeve, made by Seed of Osaka since 1968. The regular SR-100 measures 55 × 21 × 12 mm and costs ¥110 (about US$0.70) in Japan. Seed says it scored a 97% erasure rate in an industry test, and its sleeve corners are cut to stop breaks. - URL: https://stationerytimes.com/guides/seed-radar-eraser/ - Category: Accessories - Author: Ellis Penhale - Published: 2026-10-22 - Updated: 2026-10-22 ![White Seed Radar SR-100 eraser in its blue sleeve, drawn to scale at 55 mm long, with a close-up of the sleeve's cut-off corner](https://stationerytimes.com/images/raster/seed-radar-eraser-16x9.png) *The Radar SR-100 at 55 mm long, in its blue sleeve (drawn at 1 mm = 4 px).* Original drawing (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) | |---|---|---|---|---|---|---| | Seed Radar plastic eraser, SR-100 (EP-SR-100) | Seed (by Seed Co., Ltd. (Toyonaka, Osaka)) | Japan | Not stated | Plastic (PVC) eraser, phthalate-free; paper sleeve (Seed) | 1968 | $: under $5 per item | - Made in (Seed Radar plastic eraser, SR-100 (EP-SR-100)): Not stated. Seed's Japanese product and company pages (read in full on October 22, 2026) don't say where the Radar is made. Seed lists a head-office factory in Toyonaka, Osaka, and a subsidiary, SEED VIETNAM CO., LTD., in Hanoi, so the factory isn't certain. Check the sleeve. ## Key takeaways - Seed lists the Radar SR-100 at 55 × 21 × 12 mm (2.2 × 0.8 × 0.5 in) and ¥110 (about US$0.70) with tax, JAN 4906643015097. - Seed sells 5 standard sizes, from the SR-70 at 43 mm to the SR-360 at 80 mm, ¥77 (about US$0.50) to ¥396 (about US$2.50). - Seed says the Radar scored a 97% erasure rate in the Japan Eraser Manufacturers Association's test. - The Radar went on sale in 1968; Seed says it pioneered the PVC plastic eraser. - The 2025 Matoma Radar, same 55 × 21 × 12 mm size, adds a sticky resin so crumbs clump together. ## What is the Seed Radar eraser? **It's a white plastic block eraser in a blue paper sleeve, made by Seed Co., Ltd., an Osaka eraser maker founded in 1915.** In Japan it's known as "the eraser in the blue case," and Seed calls it a long seller for drafting, office and school work. Seed says the Radar went on sale in 1968 and that it was among the first to make an eraser from PVC. JetPens' June 2026 eraser guide rates the newer Matoma Radar's erasing "very high," and the regular S-100 had 331 ratings on Amazon US when we checked on October 22, 2026. ## Seed Radar SR-100 specs | Spec | Value | |---|---| | Maker | Seed Co., Ltd., Toyonaka, Osaka | | Model | Radar SR-100 (EP-SR-100); older code S-100 | | Size | 55 × 21 × 12 mm (2.2 × 0.8 × 0.5 in) (Seed) | | Weight | 19 g (Amazon US listing) | | Material | Plastic (PVC), phthalate-free (Seed) | | Erasure rate | 97% in the Japan Eraser Manufacturers Association test (Seed) | | On sale since | 1968 (Seed) | | Japan list price | ¥110 (about US$0.70) with tax | | Price band | $ (under $5) | | Made in | Not stated | ![Seed Radar SR eraser sizes drawn to scale: SR-70, SR-100, SR-120, SR-240 and SR-360](https://stationerytimes.com/images/seed-radar-eraser-sizes.svg) *The five Radar SR sizes from Seed's Japanese spec table, to one scale.* ## What sizes does the Seed Radar come in? **Five standard sizes, from the pocket SR-70 to the large SR-360.** Seed's Japanese site lists them with these sizes and prices, tax included: | Model | Size | Japan list price | |---|---|---| | SR-70 | 43 × 18 × 12 mm (1.7 × 0.7 × 0.5 in) | ¥77 (about US$0.50) | | SR-100 | 55 × 21 × 12 mm (2.2 × 0.8 × 0.5 in) | ¥110 (about US$0.70) | | SR-120 | 55 × 24 × 12 mm (2.2 × 0.9 × 0.5 in) | ¥132 (about US$0.80) | | SR-240 | 75 × 33 × 13 mm (3.0 × 1.3 × 0.5 in) | ¥264 (about US$1.70) | | SR-360 | 80 × 39 × 15 mm (3.1 × 1.5 × 0.6 in) | ¥396 (about US$2.50) | Seed also sells big and extra-big Radars and colored, clear and black versions; the regular white SR-100 is the classic. ## How well does the Radar erase? **Seed says it recorded a 97% erasure rate in the erasing test set by the Japan Eraser Manufacturers Association.** Seed describes the feel as mild, and says the crumbs aren't dry and powdery, so they don't scatter and are easy to clean up. That's a maker figure from an industry test, not an independent comparison. Like the [Tombow MONO](https://stationerytimes.com/guides/tombow-mono-eraser/) and the [Staedtler Mars plastic](https://stationerytimes.com/guides/staedtler-mars-plastic-eraser/), it's sold for pencil and mechanical pencil, not ink. For the Radar beside the Tombow MONO, Dust Catch and other Japanese erasers, see our [best Japanese erasers](https://stationerytimes.com/guides/best-japanese-erasers/). Seed's [Kadoloop](https://stationerytimes.com/guides/seed-kadoloop-eraser/) is the same 55 mm length but lets you restore a worn corner with hot water. ## Why is the sleeve cut at the corners? **To stop the eraser snapping.** Seed says the cut-off corners of the blue sleeve spread the pressure that builds where the eraser meets the sleeve edge, the place most erasers break. Seed lists the regular Radar as phthalate-free and as meeting Japan's Green Purchasing Law, and it appears on the GPN eco-products database. ## What is the Matoma Radar? **A 2025 Radar that catches its own crumbs.** Seed says the Matoma Radar (EP-RMM-100) has a special resin that makes the crumbs sticky, so they clump instead of scattering. It's the same 55 × 21 × 12 mm and ¥110 (about US$0.70) as the SR-100. Alongside it, Seed launched the Sarasara Radar (EP-RSS-100), with micro powder for a lighter erasing touch. If you want crumbs that gather, compare the [Tombow MONO Dust Catch](https://stationerytimes.com/guides/tombow-mono-dust-catch-eraser/). ## Where is the Seed Radar eraser made? **Seed doesn't state the country on the pages we read.** The company lists a head office with a factory in Toyonaka, Osaka, and a subsidiary, SEED VIETNAM CO., LTD., in Hanoi, Vietnam. The brand is Japanese. If origin matters to you, check the printed sleeve. ## Frequently asked questions ### How big is the Seed Radar SR-100? Seed lists it at 55 × 21 × 12 mm, about 2.2 × 0.8 × 0.5 in. The SR-120 is the same length but 24 mm wide. ### Why are the corners of the Radar sleeve cut off? Seed says the cut corners spread the pressure on the eraser, so it's less likely to snap at the sleeve edge. ### What is the difference between the Radar and the Matoma Radar? The Matoma Radar (EP-RMM-100), from 2025, has a resin that makes the crumbs stick together so they're easy to sweep up. The standard Radar is tuned for a mild feel and strong erasing. ### Is the Seed Radar the same as the Radar S-100 on Amazon? The S-100 is an earlier code for the regular Radar; Seed's site now lists the regular size as the SR-100 (EP-SR-100), at the same 55 mm length. ### Can the Seed Radar erase pen? No. It's a plastic eraser for pencil and mechanical pencil, sold for drafting, office and school use. ### Is the Seed Radar eraser made in Japan? Seed doesn't say. It has a factory at its Osaka head office and a subsidiary in Hanoi, Vietnam, so check the sleeve. ## Sources - [シード: レーダーSR (Seed Japan product page: SR-70 to SR-360 sizes, prices and JAN codes, 97% erasure rate, cut sleeve corners, phthalate-free; read October 22, 2026)](https://www.seedr.co.jp/products/radar-sr/) - [シード: RADERブランド (Seed Radar brand page: on sale since 1968, history, PVC plastic eraser pioneer)](https://www.seedr.co.jp/raderbrand/) - [シード: まとまレーダー・サラサラレーダー (Matoma Radar EP-RMM-100 and Sarasara Radar EP-RSS-100, 55 × 21 × 12 mm, ¥110)](https://www.seedr.co.jp/products/10351/) - [シード: 会社概要 (Seed company profile: founded 1915, head office and factory in Toyonaka, Osaka; SEED VIETNAM CO., LTD., Hanoi)](https://www.seedr.co.jp/company/) - [JetPens: The Best Erasers (June 16, 2026; comparison table rates the Seed Matoma Radar's erasability Very High)](https://www.jetpens.com/blog/The-Best-Erasers/pt/597) - [Amazon US: Seed Eraser, Radar 100 S-100-30P (2.4 × 5.5 × 1.2 cm, 19 g; 331 ratings on October 22, 2026)](https://www.amazon.com/dp/B00F9UQDC0)