This is a triple bolted high security door with security hinges. It comes with its own frame and was easy to fit to the studs (using stainless steel bolts through the studs). The door weighs around 70kgs. I had tried to use a lower cost zincalume door, but it tended to jam in the metal door frame I had and was a bit flimsy. The colour didn't really match the silver of the observatory, but I had to put functionality first! The observatory is more secure than our house - they may kill me, but they're not getting their hands on my telescope!!