Both A-style and two F-style (SMG3 and SMNI3) tuners turn in the non-conventional guitar direction.
The SMNI4R and SMG4R F-style tuners turn the conventional guitar direction.
Both styles have 23mm post to post hole spacing (29/32″) and a gear ratio of 16:1.
A 10mm (3/8″) post hole is required. Screws and bushings are included.