This handy shop aid has remained more or less unchanged since we introduced it in the 1970s, and is still relevant today. To use, just engage the end of the J-bend or straight pull spoke in the oblong hole and read its length on the scale. With both metric and SAE length markings, The SBC-1 is also handy as a general-purpose ruler. Features gauge holes for quickly and easily determining the size of most common ball bearings and crank cotters. Anodized aluminum with embossed markings for easy reading and a lifetime of use.