Park Tool SBC-1 Spoke ruler Cotter and Ball Bearing Gauge. This handy shop aid is ideal for sizing spokes ball bearings and crank cotters."
Has both metric and fractional spoke length markings
For Spokes: Hang the head of the spoke in the oblong hole and read its length on the scale
For Crank Cotters and Ball Bearings: Works just like a gauge for drill bits
Anodized aluminum with embossed markings to allow easy reading and long life