Replaces part number 15596 It is compatible with most Vita-mix blender jars such as 5200 5000 5300 6300 750 760 1230 Use this accessory to easily unscrew the retainer nut and remove the blade and reinstall the blade assembly. It does NOT fit Maxi 4000 containers This tool only fits retainer nuts that have the straight opening across. Do not purchase if it has other shapes or two holes.