its a v-belt, not a toothed cam belt, a 13mm (lockbolt)and 19 or 22 mm spanner to undo the tensioner, the adjuster/tensioner is like a cog with a nut head on it that you turn to tension the belt after you have released the lock bolt, although there are alot of mk2's out there which just have a 13mm bolt straight through the hanging bracket, you'll see when you look.