Features: *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 surface has no casting defects such as cracks, pores, looseness, etc., ensuring tight connection. *The kit contains 3 replacement piston rings(Including 2pcs balance ring+1pcs seal ring), which can replace the old or damaged ones on the air pump at any time. *Suitable for air compressors and air pumps with a cylinder diameter of 42mm/47mm/48mm/51mm/52mm/65mm, and need to be replaced when the axial clearance is greater than 0.13mm. Specifications: *Item Type: Air Compressor Piston Ring *Compatible for: Air Compressor *Size: As picture show *Applicable cylinder diameter: 42mm 47mm 48mm 51mm 52mm 65mm, Please Choose the right size. *Quantity: 3pcs Package Contents: 3 x Air Compressor Piston Ring Note: 1. The real color of the item may be slightly different from the pictures shown on website caused by many factors such as brightness of your monitor and light brightness. 2. Please allow slight manual measurement deviation for the data.