For Hydraulic Pipe Pumps, Hydraulic Fittings, And O-Ring Seal Kits,, Ring Kit. High Quality: Made of Nitrile (NBR) 90 shore material,are durable,high temperature resistance,anti static,oil resistant,UV resistance,heat resistant,wear resistant. Multi size: This handy kit contains 396pcs NBR o-rings in the 36 most popular sizes used on Caterpillar equipment. Wide Application: O-ring kit use for Caterpillar excavator. Handy Packing: Comes with a heavy duty storage case that keeps each size o rings separated and organized,that makes more convenient to carry, select and collect. Customer Service: You are unhappy for any reason, return your kit with no questions asked and BUSY-CORNER will provide a full refund.