A de facto standard devised by Roland for connecting guitars and basses equipped with a hex pickup to a guitar synthesizer. The cable carries the audio signal from each of the 6 individual coils of the hex pickup to the synth for processing and analysis. The interface also provides +/- 7V DC power to the guitar's electronics. Additionally, it can carry a few control signals from controls on the guitar, and a mono signal from the guitar's conventional pickups. A number of guitar companies manufacture guitar models that come equipped from the factory with the 13-pin interface and the necessary onboard electronics. As for synth manufacturers, the main one supporting the interface besides Roland itself is Axon.
Roland introduced this interface with the GR-50 guitar synth in 1989. Earlier Roland guitar synths, including the GR-500, GR-300 and GR-700, used a 24-pin cable and connector. This provided more routing for putting synth controls on the guitar, but it was less reliable, and guitar players disliked having to drag around the heavy 24-conductor cable.