From Amazon
Bosch Professional 6 pcs. Straight Router Bit Set (for Wood, Ø 6 mm Shank, Accessory Router)
Conrad Electronic
Groove milling cutter set, 6-mm shaft, 6-part Bosch Accessories 2607017465
OnBuy
Bosch Professional 6-piece groove cutter set (for wood, for routers with 6 mm shank)