20 mm x 1.5 Bottoming Tap, High Speed Steel
High Speed Steel. Bottoming Style (Bottoming Taps have 1-2 threads of lead, for threading close to the bottom of a blind hole.) Ground Thread. Please note that not all bottoming taps are flattened at the end. Some manufacturers leave a point that you may have to grind off if going very close to the bottom of a hole.
