when releasing the heel pivots on the fibula/tibia axis so it puts less strain on your knees.
they don't pre-release,
when they do release they do it super-smooth so you can run a high din w/o being afraid of blowing out a knee.
no wide brakes; bend them; multiple threads on how to avoid bruising your knuckles on tgr (look for vise method)
why did they stop making them anyway? cheaper to make the px series?
for that matter why did they stop making the full 360 degree turntable heels(FKS/look p18)? now those things rock!!