It pops off. On a good note if you get the bright colors, once it pops off it acts like a marker to where to start looking for blood. You do have to use a fall away type rest. PM me you address and ill mail you a couple if I still have them.
I have been contemplating buying some to give them a shot. Only real advantage to them I see is if we lived out west where the wind can play a big part. There is a whole thread on archery talk from the guy who made them with his video where he runs tests against vanes
I used them the past three years. I get better arrow flight than any feathers or vanes that I've tried. They are especially good in windy conditions (cross winds)compared to vanes, and they are great with broadheads. I've had no problems at all with them, and expect that will be what I use this fall.