Its sealed tighter than a virgin sown shut. Afaik its basically only used for parta. I was debating buying it for a spare key, shutter cap and tailcap. They are almost impossible to open and they are made and sealed for this purpose
Yes, I heard it's pretty hard to open. They put epoxy or some superglue to seal the head. However, I do remember awhile back that a member broke it loose using a strap wrench. I wish I could remember what thread that was.