This is the Jay XTC proto, the production ones are the same just different colours. Jay makes the Dynabar too, this is the 11" Dynabar and gives the most side to side travel of any spreader bar on the market and will fit any harness except single strap RE harnesses.
My backup harness is a RE carbon with the single strap but the V2, still comfy but does not allow the same side to side travel.
Spreader bar width is very important when choosing and getting the right fit with any hardshell harness, if the spreader is too narrow for your keg, then it will pinch in the sides of the harness and this can give you sore lower ribs. If the spreader is too wide it will ride up over your ribs and lead to soreness and potential injury too.
Mid size kegs need a combo of either size M or L in the harness and 8 - 13" in the spreaders.