... 2401 standard 1. NBR rubber O ring kit/o ring assortment features :1) Model No. : O ring kits /o ring assortment 5B2) Material : NBR ,FKM, EPDM ... 382 pcs, JIS B 2401 standardCatalohue Details : Model No. O ring kits/o ring assortment 5B Material NBR ,FKM, EPDM, MVQ(Silicone) Color ...