I am working on several non-tilt double pane Alenco windows in my house. I have found all the channel balancers, shoes, top guide, etc. that I need on your website. The only part that I cannot identify is the side sash guide. The guides are 5/16" square and 3/16" overall thickness. They have a lip on one edge to hook around the frame. The other edge has a 1/8" round nub that fits into a hole on the frame to secure the guide to the window frame. The guide material appears to be a hard black rubber.