This is a simple needle safety cover for used hypodermic needles with a locking mechanism. Astronauts must take injections pretty often when they are in space. Usually, with a hypodermic needle, you only get one use out of it and then you would throw it away. But with this safe needle cover on, you could save your own needle and get multiple uses out of it. You can't share needles with anyone else though. The needle won't be contaminated because it is very secure due to the locking mechanism. This can be useful in space when you could only bring limited items.