From the Ultra Fit line of stainless spurs by Herm Sprenger of Germany, this model spur has a 35mm (just under an inch) neck and a solid 20mm (3/4") wide disc. These are so much more solid than some of the knock-offs; there is a difference. Also, the shape of the spur is designed for the dressage/stiffer boot fit.
This is a one size spur/unisex. It has a slightly wider fit, for stiffer boots