Draft stopper weather strip seals the gap between the stationary window and the sliding glass door when a slider pet door panel is used.
This weather strip works with any of them, including the Thermo Panel 3e, Ideal Fast Fit, Hale Standard Panel, and Ideal VIP. Its purpose is to seal the gap that is left when installing a pet door in a sliding glass door or window. With the slider open the frames in the middle no longer seal, so there will be a hole from the top to the bottom of the door about an inch wide. This piece looks like a squeegee blade with double sided tape on one end. The proper way to install this is to peel and stick it to the back end of the slider with the weather strip just barely touching the glass on the other side. Although it looks like a squeegee blade it shouldn't be used like one; if you press it hard against the glass it will make the door very difficult to open.
This weather strip can be doubled up. You can install one on the back of the slider, then put a second on the outside frame with the blade facing in towards the sliding door. A double barrier is good for extremely cold or hot areas.