
The trap bar overhead press is a variation of the barbell overhead press and is an exercise used to target the muscles of the shoulders. You will also indirectly target the muscles of the triceps and traps when performing the trap bar overhead press.
One would use the trap bar overhead press instead of the barbell variation if they are experiencing joint pain in the shoulder which can be exacerbated when using a pronated grip on the bar. The neutral grip, as seen used in the trap bar overhead press, can help to alleviate some of that tension.