The subject was brought up in a different thread and I thought it was an important one. I can not imagine towing without any type of air assist. My primary purpose the first time I installed them was to prevent rubbing of my lowered truck but now I feel that they helped my towing experience so much that I can not have a truck without them. Everyone from mid size suvs to 1 ton trucks can benefit from these. Some vehicles have this stock (option on some GM suvs) but for those who don't:
Coil Spring application:
3/4 and 1 Ton:
1/2 Ton:
Optional but I recommend air compressor system: