I've had this installed for about a year now and am using it with a Toyota Tundra and 30ft trailer. I wouldn't be happy if I didn't buy an onboard compressor. So this is a great product. I release the pressure when I lower the chassis and that reduces the pressure on the clutch. The compressor automatically maintains 7 pounds of pressure to prevent bags from collapsing. I have a 12 volt battery operated compressor, but I can't imagine having to add or remove air every time I plug or unplug it. I'll probably be driving with hard bags all the time, which makes driving without a trailer uncomfortable. Instead, I just press and hold the button until I reach the desired level. Towing, I drive them for about sixty pounds. I highly recommend this product. It ensures the correct focusing of the headlights and improves driving comfort with a large rear load.