My second order on these. The covers are snap on, but do hold tight enough that is no problem at all (you can easily pry off with a screwdriver). Very handy for projects. I am using them to make power banks out of old lithium cells.
Good Quality, Nice finish, no burring or extra plastic. Slightly reflective (not dull finish).
Good size for Arduino or similar or other smaller electronics.
Lid fits case snug.