I got mine from Pacific Aerosport. I think they were $35 each, but that was a few years ago. To me, the great advantage of these sleeves is that they dont require modification to the glider, they simply push onto the end of the control connection, takes 2 seconds. I believe the Uerling sleeves need to be "installed". To hook up the controls, you just push the plunger down, make sure the ball is in place, release the plunger, then rotate the sleeve 180 degrees so the ball can never come out of the socket, regardless of plunger position. Works great.