1/4 NC / ANC / UNC tap [Bottoming]
TAP size 1/4 UNC or ANC tap or NC = 1/4 x 20 UNC or ANC or NC taps in taper second bottoming / plug.
These taps cannot be compared with other suppliers, as they are superior 1st quality taps. They are used for cutting internal threads in most steel, including stainless. If our taps are cared for & used correctly then they should last a long time.