1、High quality material can make sure the durability and stability of the product, with good sealing 2、When the axial clearance of the gas ring is greater than 0.13mm, you should replace the piston ring 3、Professional design and reasonable structure, easy to install and disassemble 4、The piston ring outer/inner diameter is 54/48mm, which is convenient to replace the damaged one 5、Suitable for cylinder diameter 51mm, cylinder 51mm, 1.1/1.5KW motor, 0.12/0.17 air compressor and air pump Item Type: Piston Ring Model: 51 Piston Ring Drive Mode: Pneumatic Piston Ring Outer Diameter: Approx. 54mm / 2.1in Piston Ring Inner Diameter: Approx. 48mm / 1.9in Cylinder Diameter: Approx. Approx. 51mm / 2in Applicable Models: Cylinder diameter 51mm, cylinder 51mm, etc. 1.1/1.5KW motor, 0.12/0.17 air compressor air pump accessories Description: [51 Piston Ring] The number "51" means that the cylinder diameter is 51mm 3 x Piston Ring