540-pcs copper washer kit is a set of assorted copper sealing washers in various sizes, used to prevent leaks and ensure secure fittings in mechanical and fluid systems. SPECIFICATIONS -Material: Pure copper (annealed, soft for sealing) -Total pieces: 540 -Number of sizes: 30 (from ID 4 mm to ID 33 mm) -Dimensions range: -Inner Diameter (ID): 4 mm – 33 mm -Outer Diameter (OD): 8 mm – 39 mm -Thickness:1mm – 2mm varies by size - Packaging: Plastic compartment storage box with size chart