The Gilbert aluminium rugby studs are high quality aluminium studs. Each rugby stud is individually BSI kite marked. The Gilbert aluminium rugby studs are packaged in blister packs. They are available in either 18mm + 21 mm combination (12x18mm + 4 x 21mm) or 15mm + 18 mm combination (12x15mm + 4 x 18mm) Longer studs are used to give you extra grip if the ground is exceptionally soft. The 4 longer studs in the pack are used for the heel of the boot. This pack contains: 18mm + 21 mm combination (12x18mm + 4 x 21mm)