Wera 05057675001 897 4 imp r impaktor bit holder retaining ring and ring magnet wera 05057675001 this bit holder from wera is suitable for use with impact drivers and is fitted with a retaining ring and ring magnet and so can be used to hold longer or heavier screws and for overhead work suitable for bits with 1 4in hexagon head drive wera 05057675001 897 4 imp r impaktor bit holder retaining ring and ring magnet