Compiled from 6 sources; we haven't tested this product ourselves yet. How we research
Quick answer
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.
On this page10 sections
The Radar SR-100 at 55 mm long, in its blue sleeve (drawn at 1 mm = 4 px).
Plastic (PVC) eraser, phthalate-free; paper sleeve (Seed)
Released
1968*
Price range
$under $5 per item
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Notes on these facts
Made by Seed Co., Ltd. (Toyonaka, Osaka). Country of manufacture 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. Price: example listing. Released: Seed says the Radar went on sale in 1968; the current SR codes replaced older ones such as the S-100 still sold on Amazon.
Price bands are typical US retail, checked October 2026. Conversions to US dollars are approximate, at October 2026 rates (US$1 = ¥158 = ₩1,330 = NT$32.5 = CN¥6.7 = SEK 9.9 = DKK 6.7 = ₺49.6 = C$1.41 = A$1.43 = CZK 21.7; €1 = US$1.12; £1 = US$1.32; CHF 1 = US$1.21).
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
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 and the Staedtler Mars plastic, 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. Seed’s Kadoloop 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.
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.
