Skip to content
We are closed for the winter. Place your order now to be the first in line when we reopen production in April 2027.
We are closed for the winter. Place your order now to be the first in line when we reopen production in April 2027.

Perfect Fit Guarantee Policy

If your window insert doesn’t fit perfectly, we’ll remake it – free of charge. 



Even if the measuring mistake was yours.

Email us at info@martinsonmanufacturing.com and tell us what needs adjusting. “Make the width ½ inch shorter.” “Tighten the height.” Whatever it takes. We’ll cut a new one and ship it the next business day. 

We don’t leave customers stuck with something that doesn’t work.

Step-by-step measuring video guides you
Universal hose design fits every AC unit
Every order reviewed before fabrication
If it doesn’t fit, we remake it for free
Build Your Perfect Casement Insert
Trusted by thousands of homeowners who needed a real casement window solution.

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.

Quick Links

Our Promise

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.

Contact

Martinson Manufacturing
705 Schoenhaar Dr #101
West Bend, WI 53090
info@martinsonmanufacturing.com
© 2026 Martinson Manufacturing. All rights reserved.
Web Design Company