Seal and Prevent Leaks in Plumbing, Machinery and More. The Neiko 50444A 419-piece O-ring assortment is a comprehensive MM sized set of nitrile butadiene rubber (NBR) rubber o-rings, perfect for personal use, or in professional workshops and garages. O-Rings, sometimes referred to as o rings, orings or toric joints, are used in a variety of trades for sealing and leak prevention along material joints. The super durable, yet pliable NBR rubber used in this set is highly oil and UV resistance, making these o-rings ideal for use in plumbing, machinery, hydraulic and pneumatic applications. These o-rings also feature universal compatibility, presented in 32 variations sized using the MM standard. A hardshell case is included for protection and organization of o-rings by size, along with a chart detailing their inner and outer dimensions and their location in the case. Nitrile rubber seals prevent leaks in fuel or water plumbing, machinery, hydraulic, and pneumatic connection. Provide secure seals for any oil, air, gas, and water seal application such as tap faucet, sinks, filters. Also used in miscellaneous items such as pipes, pumps, solenoids, gauges, sensors, trucks, cars, motorcycles, boats, engines, paintball guns, spray guns, pressure washers, and more. Assortment Includes:23 O-rings each in sizes: 7 x 1.5mm, 10 x 1.5mm, 13 x 1.5mm20 O-rings each in sizes: 3 x 1.5mm, 4.4 x 2mm18 O-rings each in sizes: 5 x 2mm 14 O-rings each in sizes: 10 x 2.5mm, 13 x 2.5mm, 16 x 2.5mm, 18 x 2.5mm, 21 x 2.5mm13 O-rings each in sizes: 11 x 2.5mm, 14 x 2.5mm, 19 x 2.5mm, 22 x 2.5mm10 O-rings each in sizes: 18 x 3.5mm, 20 x 3.5mm, 22 x 3.5mm, 23.5 x 3.5mm, 25 x 3.5mm, 26.5 x 3.5mm, 28 x 3.5mm, 30 x 3.5mm, 31 x 3.5mm, 33 x 3.5mm, 34.5 x 3.5mm, 36 x 3.5mm, 38 x 3.5mm, 41 x 3.5mm, 44 x 3.5mm, 47 x 3.5mm, 50 x 3.5mm1 - Hard case with chart