I decided to design this mount because the only other top mount gopro mounts for the dye i4 masks were $15-$30 dollars USD  so i'd thought i'd make a simpler more affordable version. The hardware i used to mount this on my mask was EVERBILT nylon lock nuts (M5-0.8mm) which is used to mount the gopro case, EVERBILT socket cap screws metric plain (m4.5x35mm) which you use to hold the gopro mount itself in place, and EVERBILT (m4-07) metric nylon lock nuts to hold the mount in place on the under side. you can usually find these hardware pieces at a homedepot or lowes.