When you are dealing with an interior door, the situation is a little simpler because anti-theft is not used on these. However, most locks mounted on interior doors do not have a hub but a key that goes directly into them, so the intervention of an emergency locksmith is necessary. If you want to change the lock, what type of hub do you need to buy? The cylinder can be of various kinds: equal (with both sides equal), unequal (with a longer side and a shorter one), and semi-cylinder (with only one side).