Stud sizing is based on back & front studs.
For example a 11mm x 13mm tube will include 8 11mm studs (4 for front of each boot), & 4 13mm studs (2 for back of each boot).
These are the standard M5 screw-in thread found on most soft-ground boots from Nike, Puma, Mizuno, New Balance, and Under Armour. If you're unsure, take a stud out of your boot and measure the thread — if it's roughly 5mm, these will fit. Or send us a photo and we'll confirm.
If they don't thread in properly, get in touch and we'll sort out a return as long as they haven't been used.