1.) The slingshots at the top are based on designs appearing in the early 1970's. The brace rests on the top of the forearm, and does not lock around the wrist. When the shooter draws the powerbands back, the handle must be tightly grasped to prevent it from flying out of the hand. The hand and arm can tire quickly, and aiming can be difficult.
2.) The bottom picture shows the shooter relaxing his hand while drawing back to aim. With the slingshot "locked" securely around the forearm, the handle does not have to be gripped. Concentraton and aiming is made easier since the hand can be held steady without wasting energy before shooting.
Trumark manufactures only wrist-braced slingshots that have braces which lock around the wrist. Slingshots designed this way have a built in safety feature, enhanced accuracy, and offers the shooter extra fun and comfort while aiming and shooting the slingshot!