All of our items with a screw use a 1.5mm Allen Key with an M3 (3mm), cup point socket screw. Most items use a 6mm long screw and our silver chains use a 3mm long screw.
Our older collars used a 2mm screw, and our older stainless steel chains used a 0.05 inch standard screw. If you have an older item and are not sure of the screw size you need, please contact us.
Replacement key sets are available for both sizes.