The ksd g3 has a lip which rests against the lip of the shaft/head of the penis. I found that the foreskin can get caught a little but after a while it seems to get used to any pinch points. It may sting a little at first but the pain soon goes away. Erections are restricted to the very end portion of the cage. I found when my cock pulsed during an erection the device really presses down on the penis.
I found this to be a little painful. It almost made me jump up from the sofa when it first occurred. I would say that this would probably make me think twice about trying to masterbate in a cage in future.
