1、With standard inner and outer diameter size, it is convenient to install and disassemble. 2、There are no cracks or pores on the surface of these piston rings, and good air tightness can be ensured when connecting. 3、The function of the piston ring is to maintain the air tightness between the piston and the cylinder wall. 4、The kit contains 3 replacement piston rings, which can replace the old or damaged ones on the air pump at any time. 5、Suitable for air compressors and air pumps with a cylinder diameter of 47mm, and need to be replaced when the axial clearance is greater than 0.13mm Item Type: Piston Ring Kit Model: 47 Piston Ring Drive Mode: Pneumatic Piston Ring Outer Diameter: Approx. 50mm / 2in Piston Ring Inner Diameter: Approx. 44mm / 1.7in Applicable Models: Approx. 47mm / 1.9in cylinder diameter for Outstanding/Jaguar 1P/2.5P/3P/4P air compressor air pump accessories 3 x Piston Ring