Creative Hobbies E237 Childproof Safety Key for Wind Up Music Box Musical Movements, 5/8 Inch Long Silver - Wholesale Lot of 8 Keys This offer is for a Pack of 8 Childproof Safety Winder Keys for Wind Up Music Boxes. Once screwed on to the winder post of standard wind up music boxes these keys cannot be removed. Prevents children from swallowing the keys so the music box movements can be used in toys and stuffed animals. Keys have a round collapsible flap knob so there are no sharp edges Bright nickel finish. Size refers to the overall length of the winding key post section only (does not include the round flap).