1. Wings attach to the BC using two bolts that go through the two holes you'll see in pictures of the wing, and down the centre of the backplate. If using a single tank adapter, the STA will come with longer bolts. The raised ridge in the backplate is where the nuts on the bolt sits, so it doesn't protrude through and poke you in the back.
2. The tank attaches using cam straps, 2 on Halcyon setups. For single tanks, the cam straps either pass through slots in the STA, or through slots in both the wing and backplate on later model Halcyon Pioneer setups. For double tanks, there are no soft cam straps, the same bolts that hold the wing and backplate together pass through the steel tank bands holding the tanks together (although the bolts are longer again).
3. Integrated weights - using a stainless steel backplate and single tank adapter can add up to 14 pounds integrated weight to your setup. Using an aluminum backplate and no STA can reduce this to as little as 2 pounds. Halcyon manufacture the "ACB" (active control ballast) pockets, which are weight integrated pockets which can hold up to an additional 30 pounds of weight, much like a weight integrated BC.
As you might be able to tell I own a Halcyon
Don't know a lot about the other setups but other people on this board can probably add to this.
One thing to keep in mind though is a number of people (including FredT on this board, and others on eBay) manufacture their own aftermarket backplates and harnesses, so you can get set up a lot cheaper than an initial browse of a website such as Extreme-Explorer might suggest. Most wings will attach to most makes of backplates, I think the holes are a standard 11" apart to facilitate this.
ben
