This O-ring set is made of industrial-grade nitrile rubber (NBR), known for its durability and longevity. The set includes 32 common standard sizes, ranging from 3 mm I.D. to 50 mm I.D., providing a wide variety to meet your diverse needs. To ensure easy identification and orderly placement, the O-rings come in a heavy-duty storage box. The industrial-grade NBR material used in these O-rings offers excellent oil and UV resistance, and the super flexible structure and ultra-thick wall design further enhance their durability. These O-rings are ideal for a wide range of applications, including piping, mechanical, hydraulic, and pneumatic maintenance tasks. Choose our O-ring set for a reliable and high-performing solution to your maintenance needs.