The surface has no casting defects such as cracks, pores, clearance, etc. The function of the piston ring is to maintain the tightness between the piston and the cylinder wall. Ford Cargo Air Compressor Piston & Ring Set SEB22555 I81169004 They guarantee efficient gas compression as well. Standard production, easy to install and disassemble, can be repeated and used for a long time. 3pcs Piston Ring Replacement Pneumatic Drive Air Compressor Air Pump Sealing Accessories 48mm [Long service life] Standard production, easy installation and disassembly, reusable, long-term use. The seal between the piston and the cylinder wall is good and there are no leaks. Specification: Item Type: Piston Ring Replacement Model: 48 Piston Ring Mode Driving: Tire Piston Ring Outer Diameter: Approx. Compressor Type: Reciprocating Compressor, Material: Stainless Steel, Diameter: 60 mm, Shape: Round, Surface Finishing: Polished, Usage/Application: Air Compressor, Set Content: 2 Piece Ring Expander 3Pcs 42mm Cylinder Piston Ring Pneumatic Drive Cylinder Sealing Ring... Pneumatic Piston Applicable : Approx. Drive Mode: Pneumatic. The function of the piston ring is to maintain the air tightness between the piston and the cylinder wall. Feature: 1. Air tightness between the piston and the cylinder wall is good, and there is no leakage [Good air tightness] The air tightness between the piston and the cylinder wall is good, and there is no leakage. Air Pump Piston Ring-Air Compressor Compression Piston... which ensures a firm connection.