The Unger S-channel is made from stainless steel for light weight, strength and long life.
The back of the channel features a notched design to allow the teeth of the matching ErgoTec handle (available here) to grip the rubber, so no clips are necessary, though you can use clips if you wish (not supplied).
Channel ends are rounded to protect window frames, no sharp corners!
Supplied with Unger Soft rubber.

Picture shows rear of channel.