Brake bolts

[Okeydokey]

Does anyone know the bolt size I need to put the brake calipers on my Raleigh Pioneer? Varioulsy over priced as brake caliper bolts or I believe brake boss bolts. Its the ones that secure the two brake calipers to the frame on the front and rear of the cycle. They look like M6 but there may be some hidden Shimano conspiracy that lets them charge more for four bolts? I don't have access to an M6, I am currently trying to compare photos on Google images.

Thanks in advance, apologies for the stupid question, I live in the provinces!