i got this from their site:

The EMG-89 is a dual-mode pickup. There is no electronic filtering going on to simulate a coil tap. There are two bona fide pickups in a single humbucking housing. The single coil portion of the EMG-89 is located on the logo side of the pickup. It is identical in sound to the EMG-SA. The humbucking portion is spread across the entire pickup and sounds like the EMG-85. It's perfectly OK to rotate the pickup 180 degrees to locate the single coil portion of the pickup further away from the bridge for a "beefier" tone. You may also order the EMG-89R, which has the single-coil portion located opposite the logo.

the only difference is that the single coil is on the opposite side. im guessing the R stands for reverse.

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