Replacement Viton® A O-Ring cord for splicing kit is available separately. RS Pro O-Ring Kit Viton® Metric. RS Pro O-Ring kits, available in a robust box that contains an assortment of the most popular sizes, essential for emergency repairs or routine maintenance. These kits are ideal for maintenance engineers to provide a quick and reliable choice of sealing solutions to suit the job in hand. Features and Benefits. Essential for all workshops and onsite service engineers Range of sizes – no need to purchase individual O-Rings Quick identification and easy storage for multiple O-Ring sizes Robust casing suitable for transport The kit contains 510 pieces in 18 different sizes 75 Shore A The material of the rings are resistant to petrol, oil and hydraulic oil Viton® A O-rings have a high chemical and temperature resistance alongside a low compression set. What is an O-Ring . Seals and O-rings are used to join two parts of a machine, engine or other mechanical assemblies by filling the space between both parts, creating a filled and seal space in between. This seal prevents particle, vapour and fluid leakage which in turn protects and maintains pressure whilst keeping debris out, ensuring proper function and safety.