"Keys" are really very small. Yes, the seller indicated all right, the length of the hook is 7 cm. But at the same time the seller made photo collage, where this "key" looks in the hand very large and convenient to hold. In fact, a child's finger goes through the hole with difficulty, not to mention an adult hand. In short, the door will not open for them, it remains to use it only as a rear door, to press the elevator buttons. ((( The idea is good, but the performance pumped up...