Tavia Part Number 104820 Tapered Piston Ring Compressor. Large Bore 4.820" diameter. New old stock. Tavia Performance Products fixed sized hard coat anodized aluminum tapered ring compressors allow the safest, most precise method to install pistons while preventing ring breakage. Tall height allows a gentle 1/15 pitch to gently ease the rings into their bores. Smooth easy to clean sides with finger registration groove is far superior to competitors designs. True type III mil-spec hard coat anodized. Free Shipping in the USA.