Square thread form

[1] It is the lowest friction and most efficient thread form, but it is difficult to fabricate.

The greatest advantage of square threads is that they have a much higher intrinsic efficiency than trapezoidal threads (Acme or metric trapezoidal).

[1] The greatest disadvantage is the difficulty in machining such a thread.

[1] Square threads are defined as follows by ISO standards: where Sq designates a square thread, 60 is the nominal diameter in millimeters, and 9 is the pitch in millimeters.

If there is a suffix then the value after the multiplication sign is the lead and the value in the parentheses is the pitch.