A-71010304-AI RING SETOne New Aftermarket Replacement Piston Ring Set for Zetor Tractors This aftermarket piston ring set is a direct replacement for the engine piston assembly in compatible Zetor tractor models. Piston rings seal combustion gases, assist in heat transfer from the piston to the cylinder wall, and regulate engine oil consumption. Worn or broken rings cause oil burning, loss of compression, and reduced engine performance replacing the ring set restores