I have an air ride pin box and I like to try to keep the sun off the air bag to avoid weathering of the rubber. The way I do it is use a black plastic trashbag, put it over the whole assembly, bunch up all the slack in the bag up underneath to keep it from looking unsightly and making noise in the wind, then wrap with black duct tape. Poke a small hole at the lowest point to allow water out if it gets in there. Cheap, simple, disposable. Works for me :)