Sorry you are disappointed. The "M6" referes to the thread size of bolt it is for. The hole diameter is a clearance hole - 8 mm - for that size thread. I wonder if that confused the issue? All dimensions are in the description. Remember you can always return orders for a refund if you are not entirely satisfied.
Cannot fault any part of the order from start to finish. Easy to order, kept me up to date with the order process and delivered when they were supposed to be.