Brand New ProComp Set of 8 Non-File Back Moly High Performance Piston Rings, 4.000" Bore, Metric (Part #4536). These piston rings are designed to stand up to the rigors of racing and high performance street use while providing long lasting life. Non-file back moly piston rings fit matching bore sizes without requiring custom filing to achieve proper end gap. Features: Plasma-coated, barrel-shaped, ductile iron top rings that seal against blow-by when the piston rocks in its bore. Tapered secondary rings that seal against the oil control rings upper surface for excellent oil control. 3-piece oil rings with stainless steel expanders that provide accurate tension without the loss of any horsepower. Sold in sets of 8. Specs: Piston Bore Size: 4.000" Top Piston Ring Facing Material: Plasma Moly Top Piston Ring Material: Cast Iron Top Piston Ring Thickness: 1.5mm Middle Piston Ring Material: Cast Iron Middle Piston Ring Thickness: 1.5mm Oil Piston Ring Material: Stainless Steel Oil Piston Ring Thickness: 3mm Quantity: Set of 8