These are plastic injected guides that mount on each corner of your window and act as a roller and guide. To install they snap into place. For best results it is best to use 2 on each window. No tools are required to install them. Typically they are used on Likit windows. Dimensions of these window corner guides are 3/8 in. x 9/16 in.
Most often used by Likit windows
Snaps easily into each corner and they act as both a roller and guide
