About three years ago I have begun to retrofit my Fensterrollaeden with electric Gurtwicklern. I have grown up on a belt winder models of Rademacher (or identical from Schellenberg / Chamberlain). All provided their services perfectly. The sun sensors work perfectly. The operation of the devices is simple. However, you should attach the device as with my windows side in the reveal of two screws. Two holes are therefore due. The threading of the strap is also simple. Why need I however only 1 Hour 10 minutes for the installation, is beyond me. Nevertheless, I can only recommend the belt winders.
