These foams are designed to fit the Planck - the original ortholinear keyboard by Jack Humbert of OLKB.com
The case foam is 3mm thick and fits both LoPro and Mid/High Pro cases. Currently it will not work with the upcoming Typeau cases.
The new rev 6 pcbs do have leds on the bottom so there needs to be some minor cuts for holes where the leds are otherwise it will be a tight fit. But once that's done it works super well.
It's a must!
I have a Rev6 board without underglow LEDs and it was a perfect fit. I installed with the plate foam and they make a great combo. It seems a bit heftier now and the sound is better. I recommend it.
I had heard about people having problems with foam that was too think causing the USB connector to press on the opening, but I had no problems with this and the Drop midpro cases.
FYI: When using the plate form, continue to use the standoffs on the plate screws. I incorrectly assumed I would not need them with the plate foam, but switches were not straight and not all worked. I put the standoffs back in, and found the foam had holes sized perfectly for them, and everything worked great again.
I also have a Rev6 with underglow, and I started to install it but it was a bit tighter. I think it would work fine though. (Obviously you won't get a glow since the foam covers the LEDs, but they are already in a metal case and unused.)
Case foam is a great addition to the planck kit, it really helps dampening the "ping" a heck of a lot
It doesn't have a hot-swap socket cutout, but will still fit. I kind of like it this way, so not only it dampens the sound, but will also act as a support for the hot-swap socket which could fall out when installing switches.
Don't have the Planck yet, but the foam is good