Sam Browne belts are a combination of a pistol belt, garrison belt and a shoulder strap (and D-rings). The Sam Browne belt was named after General Sir Sam Browne VC, GCB, KCSI, (1849-98) of the British Army in India. America rigged the Sam Brown belt and used it heavily during the Spanish-American War. The strap was intended to help carry the weight of a heavy pistol or sword. Classic Military Police (current) and American Cavalry have been using the system since the Civil War. Currently used as issue by many State Police and Military Dress Parade for Special Events.
The belt was not made to go with the frog and shoulder strap, it is a different leather and only barely fits into the frog with a fair amount of force, but it looks fine and the price is unbeatable.