our S5935 is M10 x 70mm and requires a 16mm masonry drill bit. you would start off with smaller pilot holes with something like 4, 5, or 6mm, then go to 12mm for the clearance hole. It does depend on the type of substrate you are drilling into, for mortar you might want to go slightly smaller depending on the quality of the mortar but for standard facing brick 12mm should be ok. Blockwork can be tricky depending again on whether it’s a low-density aerated block, Thermalite insulation block, medium-duty aggregate block, or a heavy-duty 7N block. The best advice is, if not 100% sure, to drill a test hole in a brick or block to confirm