I put these foams in all my keyboards and changes the sound and feel (positive.) confirmed it fit in my high profile alt as well.
Two small cuts on the bottom of the foam and you’re good to go. (Massdrop changed the acrylic diffuser)
The 3 pieces of foam fit flawlessly in my ALT and removed all resonance from the case interior.
Had to do some trimming of the blue pad because of the protrusion from the underside of the top case but not a big deal.
I bought this foam for my Massdrop ALT High-Profile keyboard. It's a definite must for the ALT. The foam is cut perfectly. It fills in the space and everything sounds better. I definitely recommend MKUltra foam. They're a neat company in a niche market that's putting out good product. I CBA to cut my own foam, so I appreciate that a company like MKUltra does.
There is a elevated section at the base of the Alt keyboard, the foam cannot be placed properly into the case unless you cut the foam in half along the raised region.
After shipping many of these I've had similar reports from quite a few users. It appears Massdrop revised the manufacture of the case at some point and added that ridge inside the plate and also changed the size and shape of the magnets in the plastic piece. I am now marking foam with lightly engraved cut lines to help people make the adjustment when necessary.
This stuff elevates the Alt board, changes it's acoustics, and makes it feel premium. It was an easy install and everything fit snugly.