Martinson Manufacturing designs and produces precision window inserts for portable air conditioners. Built for non-standard windows, each insert is made to exact dimensions and engineered to fit cleanly, install easily, and perform reliably in real homes.

Every insert we build is
designed to fit your window exactly, install cleanly, and work the way it should. If it doesn’t fit right, we’ll remake it. No workarounds, no damage, no guesswork, just a solution that performs reliably in your home. Every time.