LEFT-Handed Schaller Locking keys 6R, with staggered posts, Black, 6-in-line, with screws, 16:1. Needs 10mm (13/32")-diameter mounting hole.
The posts with the holes higher above the face of the headstock are used on the E, A, and D strings, the lower hole posts are for the G, B, and E strings. This gives the strings a steeper angle off the nut.
These tuners are very popular with reverse headstock enthusiasts.