HNBR Oリング 0.21" CS x 3.6" ID | AS568-342 | ダッシュ342 | 硬度90 (8個/パック)

These seals slid right into the gland without tearing, which is a relief since the old ones were disintegrating. The 90 durometer feels noticeably stiffer than standard nitrile, but that's exactly what I needed for the higher heat range.

The 90 durometer hardness gives these a solid, snug fit that doesn’t deform when torqued down—exactly what I needed for a high-pressure seal. The -40°F rating was a big selling point for me, and they’ve held up fine in cold weather so far.

Used one to replace a coolant line seal on a truck engine that sees serious temperature swings. The 90 durometer HNBR feels noticeably firmer than the cheap Buna ones I'd been using, and it seated perfectly in that 3.6" groove without any bulging.