BT30 or BT30-ER20: which do I order?

Q: BT30 or BT30-ER20: which do I order?

Short answer: Order `BT30-ER20` when you already know the shank size you run (1–13 mm). Order a bare BT30 holder when you will change collet sizes between jobs. 7:24 taper, JIS B 6339, pull stud M12. Buying the assembled BT30-ER20 saves matching a nut and collet yourself.

Question

Accepted Answer

Short answer: Order `BT30-ER20` when you already know the shank size you run (1–13 mm). Order a bare BT30 holder when you will change collet sizes between jobs.

7:24 taper, JIS B 6339, pull stud M12. Buying the assembled BT30-ER20 saves matching a nut and collet yourself.