It's a sheet of foam, so there's not a ton the can be done right or wrong. The cutouts for keys and stabilizers were perfect, it's foam so some thin parts might shift a bit in shipping but once you get the keys in its fits like a glove, not overly tight and not flimsy loose. It doesn't really make the keyboard quieter, just kills some of the reverberations making the keyboard sound less hollow and pingy. I guess I'd describe it making the keyboard less noisy, not more quiet.
Biggest complaint would be that there's no screw holes, you can pretty easily get around this by getting things lined up and pushing a tooth pick through the mounting holes, then wiggle a little because foam will close up. This worked alright but it does make lining the screw up. Marginally more difficult, so screwing the pcb down takes an extra couple minutes. I did have one screw where the treading got gunked up when it must have gripped some foam, this prevented the screw from screwing in so I just had to pull the screw out and remove the foam from the threads. It's really nitpicking at that point though.
This is my second keyboard that I've put plate foam in, this time it's in my Tada 68 lo-profile with Aliaz 80g silent switches.
It's not "silencing foam" per say, it's not any quieter to my ear, but I lack a decibel-o-meter. However, it makes the typing experience feel so much better. your keyboard has a deeper tone, and less reverb through the aluminum chassis and pcb. The result is a more Topre like "thock" rather than a higher click. It's really satisfying, and your keyboard feels tighter and more solid when typing. I'd highly recommend this foam, it's a very affordable way to up your typing experience a significant amount.
It did a really great job of slightly quieting down my RedscarfII+ ver.c with Satanic Pandas (Holy Red Pandas) without taking away too much of that signature HP sound! Also I have to mention the awesome customer service performed here. The Tada68 (& Canoe) case foam is 2mm thick & I needed a 4mm thick case foam for my board. I made a comment about this on reddit in one of MKUltra's threads & within minutes I had a response to DM them my order no. so they could make sure mine got cut at 4mm! I will definitely be using their products in the future & recommending them to anyone looking for sound dampening after that.
Thock thock thock thock. Thock thock. Thock thock thock.