PARK TOOL CDG-2 CHAINRING DIAMETER GAUGE

The CDG-2 easily and accurately measures bolt circle diameter (BCD) in millimeters for a wide variety of four- and five-bolt chainring patterns. Made of anodized aluminum and permanently laser engraved the tool centers itself in chainring holes chainring bolts or crank armholes. The CDG-2 also includes a center-to-center distance scale and a handy reference chart listing additional mounting pattern measurements.