Captain O-Ring's 255 Piece BOSS Hydraulic BN70 O-Ring Kit includes 12 sizes and 255 total o-rings. The kit includes o-ring sizes 904, 905, 906, 907, 908, 909, 910, 911, 912, 913, 914, 916 which are used to seal straight thread tube fittings (BOSS Type) found in hydraulic equipment. This kit contains o-rings made of Buna Nitrile (70 durometer) material, also known as BN70. BN70 is the most common and most practical o-ring material used in BOSS seal applications due to its resistance to many hydraulic fluids and its flexability/sealability in low temperatures. The included size chart on the front of the kit makes sizing up o-rings quick and effortless. O-Rings are conveniently sorted by size in a shatterproof Flambeau divider box.Includes:-904 (35 pieces)-905 (35 pieces)-906 (30 pieces)-907 (25 pieces)-908 (25 pieces)-909 (20 pieces)-910 (20 pieces)-911 (15 pieces)-912 (15 pieces)-913 (15 pieces)-914 (10 pieces)-916 (10 pieces) What to expect:This item includes 255 O-Rings in a Flambeau plastic divider case with "Captain O-Ring" branded packaging.Manufactured and warrantied against defect for one year by Captain O-Ring LLC. "Captain O-Ring" is a registered trademark of Captain O-Ring LLC.