Wera 05057676001 897 4 imp impaktor bit holder with retaining ring and magnet wera 05057676001 this stainless streel bit holder from wera is suitable for use with power driven screwdrivers and is fitted with a retaining ring and magnet for a secure fit in the holder suitable for bits with 1 4in hexagon head drive wera 05057676001 897 4 imp impaktor bit holder with retaining ring and magnet