Mutual Screw & Supply

0.21" CS X 4.975" ID Buna-N Nitrile O-Rings | AS568-351 | Dash 351 | 70 Durometer | Black (50 / Pkg.)

0.21" CS X 4.975" ID Buna-N Nitrile O-Rings | AS568-351 | Dash 351 | 70 - Main image
$36.01 $52.96 In stock

Buna-N Nitrile o-rings in AS568-351, 4.975" inner diameter by 0.21" cross-section. Service range -40°F to +250°F (-40°C to +121°C). Also known as NBR, Buna-N, Chemigum, Hycar, Perbunan.

Specifications

  • Product type: O-Ring
  • Material: Buna-N Nitrile
  • AS568 dash size: 351
  • Cross-section: 0.21" (5.33 mm)
  • Inner diameter: 4.975" (126.36 mm)
  • Durometer: 70 Shore A
  • Color: Black
  • Temperature range: -40°F to +250°F (-40°C to +121°C)
  • Measurement type: Imperial
  • Pack quantity: 50 per package
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Standard Shipping: Handling (business days) 0–1; Transit (business days) 7–15.

Express Shipping: Handling (business days) 0–1; Transit (business days) 7–15.

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Standard Shipping · United States: $0.00

Express Shipping · United States: $3.99

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United States · Return window (days after delivery): 30. Return method: By mail. Return postage: Seller pays.

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Customer Reviews (5.0 / 5 · 5 reviews)

Alexander Z. ★★★★★

These were exactly the right size for a hydraulic fitting on my log splitter, and the 70 durometer hardness feels plenty durable. The -40°F rating is a bonus since I work outside in the winter, and the whole pack of 50 came well organized for storage.

Adam ★★★★★

Needed to replace the old o-rings on my hydraulic cylinder and these fit perfectly, the 0.21” cross-section seals tight without any leaks. They’re rated to handle up to +250°F, which covers my application easily.

Amelia ★★★★★

The 70 durometer feels just right for my air compressor fittings — snug seal without needing to force them on. I’ve had a bad experience with softer rings flattening out, but these are holding up well even at higher pressures.