1/4" 1/2" Shank Tongue and Groove Router Bit Set T-type 3-tooth Useful Cutter UK

With this set you can use the one bit to groove the slot and another one bit to mill the tongue. Matched Tongue and Groove Assembly with 3 Flutes to generate more balance cut. Shank : 1/2" shank. Design: Tongue & Groove.

eBay