Double Diamond Halter Designed by Buck Brannaman- Light Blue/BlackDouble Diamond Halter Designed by Buck Brannaman Light Blue Black Horse size. Designed and used by Buck Brannaman. They are 6mm (approx. 1 4) diameter with nylon core and a 16 strand nylon cover. The smaller diameter gives the horseman greater control and response. The knot on the end of the tail allows you to slip the halter over the horses head without untying the halter. These halters are available in a variety of colors.