The Press-T i'm using doesn't loosen by itself. But then again I'm using optional accessories like the anti-twist plate for my camera and anti-twist quick-release for my flash. Like i said it's very sturdy but it makes the whole setup so ungainly to handle. + it's expensive. Even though i got my Press-T 2nd hand and my extra parts from B&H, i think the total cost of the whole setup is at least S$200+.