The skid plate is what holds up the gas tank. All the straps do is secure the tank to the skid so it doesnt bounce around. You DO need a skid plate factory or aftermarket unless your running a fuel cell in your backseat. The straps go over the top of the tank, they slide through on one side and bolt down over the top on the other side. Its a good idea to drill out the rivets that hold the plastic tab on the straps, and remove them, then flip it over and pound the bends the opposite way. There is a sharp metal tab on the straps that may at some point cut your tank.
Saavy makes a lightweight aluminum skid that looks very nice. Rokmen's is made out of steel and is quite heavy and UNFINISHED.
I replaced mine about 3 months ago as my skid was rusted thru and went with Rokmen because it was a little bit more cost effective. I like it very much, however i was in such a hurry to get it on i never coated it with anything to protect it(regret.) It has gotten some surface rust already and i will be going over it with POR-15 when it gets a little warmer.
Both are made with the dimple for the fuel pump. If your not running a BL you made need the spacer kit for the Rokmen skid. Not sure about the Saavy skid.