Never got my head round this M8, M10 etc naming lark for bolts and nuts.

I need to replace some rather rounded thread-locked nuts on my bike, a 10mm spanner fits them. What do I need to ask for please?

10mm head is usually m6 IIRC

you really need to measure the thread. in mm. that is the M-

HTH

As TJ says 10mm spanner head will be a 6mm thread. If its the nuts that you are after and there is a plastic insert at the top of the nut to lock the thread you will need a M6 Ni-Lock nut.

Thanks TJ

Thanks all!