The slot cover (bracket), that the plugs are mounted on, is made of easily bendable metal, making it extremely difficult to push the mating connector onto them, without severely bending the bracket. Unfortunately this makes them almost useless. they are not made for multiple connect/disconnect cycles.
The panel is very useful especially in conjunction with two items: 1. a long Molex Extension Cable (You can get a 72in one made by OKgear from Amazon). 2. a 6ft SATA Internal Shielded Cable (Type L to Type L) Product 6264. Route it trough some hole out of your case. This setup allows you to keep your case closed and experiment with any drives outside the case.
OTOH, I have to agree with previous reviewer bracket is very flimsy, can not deal with normal force needed to insert a Molex cable (that tend not to align very well it is an old, crummy standard). But I could find anyone selling anything better, so what I plan to do is buy another one, take all the wiring off, enlarge the screw holes with a Dremel, and then use this "sacrifice" bracket to double the original one. Will see how it works.