I had a spare HackRF One PCB from a Portapack, so I purchased a Nooelec aluminium case to put it in, but the case was slightly too short for my 3rd party HackRF One PCB. So I designed this 1mm shim, one required for each end. The notches for the screws may not look like they line up perfectly, but on my case the actual screw holes were slightly uneven. It should still fit perfectly.