Well show you how this works, you just open up the latch and give it a gentle pull towards you which will bring the rack down. This is the strap that hold the ladder in place and keeps it from going anywhere. It simply works like a ratchet mechanism. Also on this assembly are the ladder stops and theyre infinitely adjustable across the whole rack as well as the ratchet strap. Lets go ahead and put a ladder on there and show you how it works. To lock everything back into place, you simply slide the latch back over. Just to let you know what you get for this part number, this system includes two aluminum tilting arm assemblies, one pair of adjusting ladder holders, four powder coated aluminum adjustable load stops and the hardware to install this on your existing Thule rack. There you have it for part number 339, the ladder tilt from Thule.