The hook is very stable, you can in one direction swings and through the plastic insert and a little WD40 quitscht it not;) The hook indeed suitable for wood and concrete but must, as already described herein, other screws to buy added since the provided Phillips screws are ill-suited for mounting in concrete, because you can not exert enough force on it. Recommendation: The same screws with 6 Kant external thread and everything is super!