Skip to content
Preseason orders will begin to ship April 1st
Preseason orders will begin to ship April 1st
Custom Portable AC Window Kit for Casement Windows

Remake for Casement Windows

This order form is only for customers who have previously placed an order with us and need a remake.
Perfect Fit Guarantee

If your window insert doesn’t fit perfectly (even if you made a mistake in measuring) email us at info@martinsonmanufacturing.com and we’ll remake it for you free of charge. Just pay $35 to cover shipping.

Shipping

Your custom order will be handed off to UPS according to the lead time shown at the very top of our website.

All orders ship UPS Ground (3-5 business days) for free.

Need it sooner? The following services are available to purchase at checkout: 2nd Day Air ($45), Overnight ($75). 

Canadian? Shipping is $22 and we pay all your import fees, including the current tariffs.

Installation

Installation takes 5-10 minutes. Window inserts are held in place with glazier push points or clear adhesive tape which come with your order. Velcro can also be used if your panel is going to rest over your window frame.

What's Included
  • Crystal clear perfect fitting window insert
  • Quick attach vent system for easy and secure hose hookup
  • Bug screens for your vent hose(s)
  • Installation Kit (glazier push points, clear adhesive tape and installation instructions)

***All orders come with a vent for a 5.9"/6" hose. If you have a 5" hose (uncommon) then let us know in the notes and we'll send you our 5" vent. Both 5" and 6" vents use the same cutout for easy exchange. In the rare instance that your hose doesn't fit the vent your received, just email us and we'll send you the correct vent for free.

Specifications
  • All panels are made from thick 1/4" acrylic.
  • The corners are slightly rounded (1/8" radius) for safety.
  • Panels are cut 1/16" shorter than the measurements given. This method will give you a perfect fit. (Most window frames are not square and cutting them to the exact size can often result in a panel not fitting. We've done this thousands of times and know what works best).

***If Hose-in-hose option was selected and your panel is less then 16" wide, the cutout will be oriented vertically to maintain structural integrity and you'll need to use the sliding window adapter that came with your unit. Our hose-in-hose bug screens are incompatible with the sliding window adapter and won't be included in your order for this scenario.

Built to Seal. Made for Casement Windows.

Generic kits are built for sliding windows. Casement windows are different, and require a different approach.



This insert is engineered specifically for crank-out windows, controlling airflow at the source so heat exhausts cleanly and indoor temperatures stay consistent.



You’re not forcing a kit to work. The insert is built to match your window exactly.

  • Custom CNC-cut ¼″ clear acrylic panel sized to your exact dimensions
  • Quick-attach vent system for secure hose connection
  • Non-permanent installation in 5–10 minutes
  • Designed to prevent hot air from re-entering your space
Build Your Perfect Casement Insert
Trusted by thousands of homeowners who needed a real casement window solution.

Precision-Built for Casement Windows

Built from durable, crystal-clear acrylic, each panel is custom made to your exact measurements. It creates a tight seal around your AC hose opening, preventing leaks and improving cooling efficiency instantly.
Custom-Fit Guarantee

Custom-Fit Guarantee

If it doesn’t fit, we remake it. Even if the measurement mistake was yours. No risk.

Crystal Clear Panel

Crystal Clear Panel

Durable ¼” clear acrylic. Strong, stable, and designed to preserve natural light.

5-10 Minute Install

5-10 Minute Install

No permanent modifications. Secure fit using a simple, non-invasive install kit.

Manufactured in USA

Manufactured in USA

Precision CNC-cut in-house. Built to order for your exact window dimensions.

Weather-Resistant

Weather-Resistant

Designed to handle heat and humidity. Maintains structure and seal through the season.

Free Shipping

Free Shipping

Free U.S. shipping. Delivered in 5–7 days.
Fast turnaround when you need cooling now.

Build Your Custom Insert Now
Trusted by thousands of homeowners who needed a true casement solution.

Install in 5-10 Minutes. No Drilling. No Hardware. No Headaches.

Measure your window, submit your dimensions, and we handle the precision cutting. Your custom insert arrives in 5–7 days and installs in under 10 minutes. No drilling, no permanent modifications.
Build Your Custom Insert Now
Trusted by thousands of homeowners who needed a true casement solution.

Seals Tight. Looks Clean. No Blocked Sunlight.

Most portable AC kits block sunlight or make your window look patched together. This custom insert preserves your natural daylight while creating a tight seal around your hose opening.
Build Your Custom Insert Now
Trusted by thousands of homeowners who needed a true casement solution.

Perfect Fit Guarantee

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.

Stop Letting the Heat Win in Your Own Home

You feel it every evening – the AC is running, the hose is humming, yet the room still feels heavy. Warm air seeps back in, the temperature never quite stabilizes, and you’re left adjusting settings that don’t fix the real issue.

That’s not an AC problem. It’s a window problem.



Generic kits are built for sliding windows. When you force them into casement frames, they leak. The system works harder, energy use climbs, and comfort never fully settles.



This insert corrects the problem at the source – the window – so your AC can cool the room the way it was meant to.



Cooler air. Steadier temperatures. Less frustration.

Build Your Custom Insert Now
Trusted by thousands of homeowners who needed a true casement solution.

Frequently Asked Questions

Yes. Our inserts are custom-built to your exact window dimensions and designed specifically for casement and other non-standard window types.
No special tools required. Our inserts install in minutes with simple hand tools. Detailed instructions included.
No. Our inserts are designed to sit securely inside your window frame without screws, adhesives, or permanent modifications.
We offer a Perfect Fit Guarantee: if your insert doesn't fit exactly, we'll remake it for free.
Yes, our inserts are compatible with single-hose, dual-hose, and hose-in-hose portable air conditioners.

Casement Windows Done Right

Portable AC units fail with the wrong window setup. This insert fixes that.
★★★★★ 4.9/5 | 1,904
Martincon Manufacturing
Precision window inserts for non-standard openings.
Call Today 123-456-7890
Build Perfect 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 #101West Bend, WI 53090
262-340-1418
info@martinsonmanufacturing.com
© 2026 Martinson Manufacturing. All rights reserved.
Web Design Company