1D piston ring product quality comparison explanation： The working surface of the piston ring shall not have nicks, scratches, peeling, the outer cylinder and the upper and lower end surfaces shall have a fixed finish, the curvature deviation shall not be greater than 0.02-0.04 mm, the standard subsidence of the ring in the groove shall not exceed 0.15-0.25 mm, and the elasticity and clearance of the piston ring meet the requirements. Under normal circumstances, the light leak seam of the piston ring measured with a thickness gauge should not exceed 0.03 mm. The length of continuous light leakage seam should not be greater than 1/3 of the cylinder diameter, the length of a number of light leakage gaps should not be greater than 1/3 of the cylinder diameter, and the total length of a number of light leakage should not exceed 1/2 of the cylinder diameter, otherwise, it should be replaced.