Brief Description: The t-slot router bits are great for creating t-channels for jig and clamp applications and the key holes for suspended designs. It is recommended that a straight groove, matching the width to the top of the "t", be cut in the workpiece before routing the t-slot to reduce stress on the bit. T-notch cuts produce a lot of wood chips with little space for them to escape and can cause the bit to get bogged down. Take it easy on the feed and back off every two inches before resuming with the cut. Specification: Type: key hole router bit Meterial: Carbide Shank: 1/4 '' 1/2 '' Cutting diameter: 3/8 '' 1/2 '' note: Please allow 1-3mm errors due to manual measurement. The color of the item shown in the photos may be showing slightly different on your computer monitor, since the monitors are not calibrated in the same way.