DIY Doctor UK DIY Forums

Something I bought came with standard hex head bolts. I want to replace these with countersunk head ones. I can't figure out what M3, M4 etc stand for on the ones I am looking to purchase. The provided bolts have YZ 4.8 written on them. Any clue what this refers to or how to convert?

Hi rosy-I’d
The xy4.8 refers to the bolt strength not size.
Measure the diameter of the bolts you have - 6mm will be M6; 8mm will be M8. The issue you may meet is the the thread pitch may vary so M8 bolts may have a thread pitch of 1.0 or 1.25mm.
Regards S