ARP Billet Bore Tapered Piston Ring Compressor 86.5mm 901-8650

This ring compressor has a tapered inner surface that helps you slide the piston into the block with the rings installed. As the piston slides down the cylinder, the rings push into the ring-lands allowing the piston to slide into the bore. Its a must-have for assembling your engine.
ARP RING COMPRESSORS

ARP’s new ring compressors are CNC machined from 6061-T6 billet
tube material and feature a true radius for each different bore diameter.
What’s more, they are relieved for wire O-rings on bottom. Type 3 anodizing
is used for long life, and the bore size is prominently engraved in 3/4?
high numbers for easy identification. Standard stocking sizes from 3.552? to
4.750? (SAE) and 75mm to 100mm (metric). The true radius design is far
superior to conventional “tapered” devices, and widely acclaimed by professional
engine builders! This is truly the very best piston ring compressor on
the market today.