Very useful in households with children. per: Can be easily and quickly install. Then plug it in and turn it to the hole positions. Child can not poke fingers. Very satisfactory. Cons: The adhesive strip on the inside is too weak for proper fixing Some say plug Hollen Parental Control back out of the Steckdoser. Wekgen the additional layer in the socket happens also that the cable out jumping again by pulling gently vacuuming the plug. For the two points star deduction.