The MultiSink pilot should be used when countersinking bolt holes from 9/16" - 15/16" diameter. The pilot helps centre the countersink for excellent performance. Use MultiSink with variable speed Magnet Drill. The speed must be reduced when countersinking.Innovative combination countersinking tool Save time completing countersunk holes Suitable for holes 9/16" and above Pilot feature gives a precise, concentric fit for excellent performance