Router cutter HW with fitted base blade

The same reversible-blade groove cutters on a 12 mm shank, from 10 to 16 mm wide and cutting deeper — up to 50 mm. The thicker shank is the point: a long cutter on an 8 mm shank flexes under load and chatters. If you are grooving deep, in hard material, or in one heavy pass, use the 12 mm and a router that takes it.