They are also appropriate for tapping the vast majority of materials in through or blind holed conditions. 6-40 HSS Machine and Fraction Hand Plug Tap Hand Taps are the most versatile taps for hand use, or for tapping under power. Plug Style: Generally used in thru holes. HSS Hand Tap, Plug, Size: #6-40, Limit H2, Number of Flutes 3 Hand taps are popular for use in general machine tapping or CNC tapping.