Good pickup mate, I won't even ask what you paid for them, it'll probably just make me cry. The air caps are great, folks here who don't know what they're talking about will tell you they were snake oil, blah blah blah, but I've had them on several bikes (and have them currently on my K1 fitted with GL1000 front end) and they work, just as designed.
What they do is take the sag out of your forks, spread your fork seals to reduce leakage, and give you the preload you need without having to revert to packing washers or other crap on top of your fork springs, so you get the full travel of your forks, and not just the last couple of inches. If your seals are in good condition, (and your forks too, of course) they'll hold air for a long time, I installed mine last year, and they're still holding air.
Be careful how you inflate them though, mine is an S&W kit with a gauge, and only run around 12 psi, so you need a bicycle pump or something similar to inflate them, the air pressure at the pump at your gas station will likely blow your fork seals out.
I can't see your rear shocks well enough in those pics to tell what they are, can you post a clearer pic? Cheers, Terry.
