Features: Gradual billet taper design precisely guides the piston into the bore without damage Adjustable diameter allows one tool to work on all stock and oversize pistons/bores of a particular engine Convenient tool-less thumb adjuster makes adjustments easy CNC machined from tempered and anodized aerospace grade alloy Works with: Fits engine bores from 83.05mm-86.87mm (3.27″-3.42″) Perfect for FA20, FA20T, and FB20 engines (fits all stock and oversize pistons/bores)