Features The rubber O-ring is made of flexible rubber to ensure a seal and prevent leakage. It can be used in pipelines, machines, in hydraulic and pneumatic maintenance and in other areas. Commercial grade nitrile rubber (NBR) The formula has excellent oil and UV resistance. Applications O-rings have been widely used by professional technicians and home decorators to repair engine leaks and other leaks such as engine oil, coolant, power steering fluid, cleaning fluid, etc. Plumbers and DIY enthusiasts can also use O-rings to seal pipes and prevent leaks in household sinks, bathtubs, and septic tanks. Size The box contains 32 common standard sizes, which are arranged according to sizes from 3 mm to 50 mm. You can see the required size at a glance. The 419 O-rings come with a heavy-duty storage box with a size chart on the lid so that each size can be arranged separately. This is easy to carry and not easy to scatter in the tool stand or tool box. Performance O-ring has super soft structure, good ductility, not easy to crack, not easy to deform, can be used flexibly for various purposes and is easy to use, its super flexible structure and ultra-thick wall design make it is strong and durable.