MITRE LOCK BIT D/F - Primarily designed for joining material at 90 Degrees, however this bit will also produce reasonably strong straight joints.
One bit is required. For 90 Degree joins cut second piece of timber at 90 Degrees to first piece to produce joint. For straight joints invert the second piece of timber for matching joint. Carbide Tipped, Two Flutes, 1/2" Shank, T Min: 8.7mm, T Max: 20mm.