Features:*The operate of the piston ring is to maintain the air tightness between the piston and the cylinder wall.*With ordinary inner and outer diameter size, it's handy to put in and disassemble.*The for has no casting defects corresponding to cracks, pores, looseness, etc., ensuring tight connection.*The equipment includes three alternative piston rings(Including 2pcs balance ring+1pcs seal ring), which can update the previous or broken 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/90mm/95mm/100mm, and want to get replaced when the axial clearance is greater than 0.13mm.Specifications:*Item Type: Air Compressor Piston Ring*Compatible for: Air Compressor*Size: As photo show*Applicable cylinder diameter: 42mm 47mm 48mm 51mm 52mm 65mm 90mm 95mm 100mm, Please Choose the right size.*Quantity: 3pcsPackage Contents:3 x Air Compressor Piston RingNote:1. The real shade of the thing may be slightly diverse from the images proven on web content caused by many factors corresponding to brightness of your monitor and lightweight brightness.2. Please allow slight manual measurement deviation for the data.