Features:* replacement piston, suitable for piston air compressors and air pump pistons.*The whole machine has simple and compact structure, light weight and flexible movement.*, anti‑corrosion, anti‑, anti‑oxidation, high temperature resistance, wear resistance.*The function of the piston ring is to maintain the air tightness between the piston and the cylinder wall.*With standard inner and outer diameter size, it is convenient to install and disassemble.*The has no casting defects such as cracks, pores, looseness, etc., ensuring tight connection.*The kit contains 1 piston + 3 replacement piston rings(Including 2pcs balance ring+1pcs seal ring), which can replace the old or damaged pieces on the air pump at any time. Specifications:*Item Type: Air Compressor Piston + Piston Ring*Material: Metal*Color: Silver, Black*Applicable cylinder diameter: 42mm 47mm 48mm 51mm 65mm, Please Choose the right size.*Hole diameter: As picture show*Application: Piston type air compressor, air pump piston*Quantity: 4pcs Package Contents:1 x Air Compressor Piston3 x Air Compressor Piston Rings