Magnetic Seal vs Compression Seal

What difference is a particular window attachment going to make to the comfort of your home? How effective is a magnetic seal or compression seal when used on a storm window? We’ll answer these questions in this blog and why Indow decided against magnetic window insulation.

Why We Said No to Magnetic Seal

When Indow first designed our window inserts, we considered putting magnets inside our compression tube, but we found that a magnetic window insulation created a lot of design flaws.

“It’s not very attractive, it’s cumbersome to install, and that metal frame remains in your window frame after you remove the insert and that’s ugly. So there were three things we didn’t like about the magnetic system.”

-Sam Pardue, Indow Founder

First, for a magnetic seal to form, magnets have to grab hold of something. That something is permanently attached to your window frame—generally a metal bracket fixed to the entire window frame needing many holes drilled into it. So it’s cumbersome to install.

Second, magnetic window insulation is not attractive either with the window insert installed or removed. If you take the window insert off, you still have a big metal bracket surrounding your window.

diagram of a magnetic window insulation system

Third, the acrylic used in most window inserts expands and contracts with the temperature. While the window insert and attached magnets move, the metal frame does not. So, whatever magnetic seal there was is broken and the whole panel can pop off.

Magnets attract in one direction, but compression tube creates spring force all the way around the window frame. It absorbs expansion and contraction in every direction and creates friction and resistance against air pressure.

So, we removed the magnet and created a window insert that relies on compression seal alone. The compression tube can do everything we need and the simplest solution is often the best solution.

woman installing Indow insert in window to create compression seal

Why Compression Seal is Better Than Magnetic Seal

The compression tube around our acrylic panels is the spring force that holds in insert in place. It absorbs all thermal expansion caused by temperature change. This ability to expand and contract creates a near airtight seal no matter the shape, size, or condition of your window. The compression tube is a seal against drafts and heat, and it keeps conditioned air inside.

close up of Indow window insert creating compression seal

A compression seal is stronger than a magnetic seal because it is better at dealing with out of square windows. If your home is older and has had time to settle, it most likely hasn’t settled perfectly straight – this causes out of square windows.

“The problem is that magnetic systems don’t always deal really easily with the fact that most window frames are really out of square. So sometimes you get a gap up in the corner, if it’s a really out of square window. With our system we’re going to make the insert the exact shape of the window opening, you’re going to get very tight seal all the way around—a nice even compression.”

– Sam Pardue, Indow Founder

Magnetic seals can get gaps because they were made for a perfectly square window frame. Compression seal adjusts for the out of square window so you continue to have a tight seal and even compression.

Our compression seal can accommodate expansion and contraction from heat and window frame inconsistencies without altering the window at all. Our compression seal is stronger than magnetic seal, fits any shape of window, and requires no hardware.

For more information read about our compression system.

Customer Reviews


4.48 Average 1399 Reviews logo

Fayette V

The inserts provided immediate results for the better. The inserts a virtually invisible which was better than expected. The biggest challenges were getting the accurate measurements which I Dow was helpful with and repositioning the blinds. Everything has worked out. We are planning to do this with other windows

Posted 3 days ago

Jamie W

We were excited to receive our Indows, but once we got them in, we were blown away! They match our woodwork almost perfectly. Installing them was far easier than we had anticipated, and we were immediately impressed by the noise reduction, as well as the ability to reduce the impact of the windows on our indoor temperature! Couldn't be more pleased and very excited to be able to add "custom" shapes for the top of our lancet windows.

Posted 1 week ago

Mark H

The acoustic indow window worked better than I expected at blocking out noise. The only thing I didn't like was the shipping company (T-Force Freight). The shipping company was difficult enough that I decided to rent a U-Haul and pick it up at their warehouse.

Posted 2 weeks ago

Venkatesh G

Indow solves my noise problem due to highway traffic. I recommend this company for noise reduce solutions.

Posted 2 weeks ago

Thomas R

The process was simple and easy. I was a little nervous having to measure everything myself...but I got the inserts and they fit in our windows perfectly without any hassle. 1000% recommended.

Posted 2 weeks ago

Dan E

As always with internet purchases, I was holding my breath on my recent purchase of inserts! However, everything suggested by everyone I spoke to via telephone, email and text, was verified when I received and installed my inserts!!! Nothing short of phenomenal; fit, sound deadening qualities, (yet to discover energy savings), and customer service is excellent!! I highly recommend this company and product!!

Posted 2 weeks ago


Good quality window inserts. Easy to install. Unfortunately, doesn't do much to block road noise that I was hoping it would help with. Website is clear on the uses so I can't say it was false advertising, just buyer error.

Posted 3 weeks ago

Tommy J

We ordered 4 Indow Window inserts to see how they worked on our steel casement windows. We are very pleased with the fit and finish, and especially the improvement in wintertime comfort. Steel casements present challenging issues when trying to improve efficiency. The only downside for our installation is it required the removal of the locking and operating hardware to work in concert with our window treatments. The attached photo is during installation with Indow inserts installed on the two left pair; not yet installed on the two right pair. Pretty minimal visual difference! I'm now ordering 17 more inserts for the rest of the house.

Posted 3 weeks ago

Catherine L

Our acoustic window inserts have definitely reduced the amount of street noise coming into our apartment. While we can still hear the train as the engines pass by the noise from the train cars is very muted. Likewise we still hear the drunken club patrons yelling, but it no longer seems like they are in the room with us. Our big negative would be that the blinds we enclosed in the space between our single pane and the insert melted and warped within the first week. I don’t think there was any mention in the directions about the possibility of heat build up and potential consequences. That might be good for people to know.

Posted 3 weeks ago

John W

Finally, a solution that doesn't break the bank and allows you to keep your existing windows. We bought ours primarily for additional soundproofing as our builder used dual-pane glass. It makes a measurable difference - 20 dB. The bonus is the insulation value. It's been a mild spring and our main bedroom at the front of the house facing the morning sun is much cooler. I suspect it will be warmer in winter as well. If you follow the self-measure and installation instructions to the letter, they go in easily. We have floor-to-ceiling windows, so we had massive inserts, but it was still manageable for two people.

Posted 3 weeks ago

Jillian G

The measurement process was overly complicated - I understand the desire to get a tight fit into not perfectly square windwos, but a 17 page manual for something you can accomplish with math felt unnecessary. I also found the interface to be a bit challenging to work with when inputting fractions that necessarily had to be rounded but the system didn't like my entry. Otherwise, the inserts themselves fit well, very tight, noticeable noise reduction. I am so satisfied with them that I am considering placing another order (depending on whether I want to also spend the money to change window treatments).

Posted 4 weeks ago

Michael M

What a great option for old homes with drafty windows! Our home's windows are so drafty that the curtains in our bedroom would move/blow when it was windy out. The communication with Indows was excellent, and our questions were answered promptly. We thought the measuring process would be a pain, and we were worried we would not be accurate enough, but the kit they sent along with the instructional videos made it very easy. The Indows were delivered in a large wooden crate, and they made it through shipping unharmed (just some dirt marks on the silicon tubing, most of it came off with Castille soap, but some dark smudges did remain on the white tubing--our only disappointment). Our windows are huge, so we installed the little safety chain provided and inserting them was a 2 person job. There was a little bit of a learning curve with the first Indow, but we can take them in and out fairly easily now. The fit was perfect, and we noticed a difference in the temperature of our home right away. Our house stayed warmer, our furnace ran less, and our curtains are no longer blowing in drafts. The product looks great, and blends right in with our woodwork! We will definitely order more for the few windows we didn't do, and we would recommend this company and product to anyone.

Posted 4 weeks ago

Lisa I

They really work! While I still hear traffic (mostly trucks and motorcycles) normal car traffic is virtually silenced. I'm still not able to sleep in the room because we get so many trucks I am able to use this room as an office space now, which was my goal. This room was once the noisiest room in my house and now I enjoy coming up here to watch tv. Thank you!

Posted 4 weeks ago