My window screens are too large!

Recently I had a phone call, "My window screens are too large, and they keep falling out"!

After reviewing the project, I discovered the window screens were missing "bale clips". Here is how these, seemly invisible, bale clips work on window screens.

When installing the screen (rotating screen 180 degrees) the bale clip (now invisible) slides upwards and "pinches" the top of the screen to the middle mullion of the window.

The screen rides on the outer channel of the window frame and sits on the outer channel of the window threshold. This would appear to be "too large" when compared to the majority of screens installed on the inner channel of the window frame. 

Removing screens (from exterior) using bale clips. Lift the screen off the window threshold, tilt the bottom of screen outward, pull screen down to release the bale clips off the middle mullion of the window frame. To install, reverse the process.