This set includes 10 copper washer seals sized 21 x 27 x 2 mm. These solid gaskets are designed for sump oil sealing and suit uses where a crush washer is required between mating surfaces. Key benefits Reliable seal: copper washers deform to create a tight, leak resistant seal between the sealing faces. Durable material: copper offers good resistance to heat and oil exposure, maintaining sealing performance under typical engine and machinery conditions. Easy to use: simple washer replacement restores sealing integrity during maintenance or repairs. Specifications and features Quantity: 10 pieces per pack Size: 21 x 27 x 2 mm (inner diameter 21 mm, outer diameter 27 mm, thickness 2 mm) Material: Copper Type: Solid gasket / washer for sump oil sealing Compatibility and performance Functionality: serves as a crush washer for oil drain plugs and other sealing interfaces requiring a copper gasket. Compatibility: suitable for sealing applications with an inner diameter of 21 mm and an outer diameter of 27 mm, thickness 2 mm. Performance: copper construction provides reliable sealing in oil sump and related oil sealing applications. Use cases Automotive engine oil sump drain plug gasket: replaces worn or damaged copper washers to prevent oil leaks. Motorcycle and small engine oil pans: seals drain plugs and other oil sealing interfaces that require a 21 mm ID copper washer. Hydraulic fittings and gearboxes: used as a copper crush washer in suitable oil sealing connections where a 21 mm ID, 27 mm OD washer is specified. How to use Prepare surfaces: ensure sealing faces are clean and of debris. Install: place the copper washer between the drain plug and oil sump surface or between mating surfaces as required. Torque: reinstall the fastener to the manufacturer's specification, allowing the washer to deform and seal. Replacement guidance: copper crush washers are intended for single use; with a washer if deformed, damaged, or after servicing. Care and notes Do not reuse crushed washers, as reusing can lead to leaks. Verify the correct ID, OD, and thickness for your specific application before installation. Store in a dry environment to prevent oxidation before use. This description reflects the product's brandneutral specifications: 10PCS per pack, copper solid gasket washers sized 21 x 27 x 2 mm for sump oil sealing, suitable for applications requiring a 21 mm inner diameter and 27 mm outer diameter with 2 mm thickness.