Another piece of information. I recently installed an ESG along with its included GPS antenna and, in planning for a possible future panel GPS navigator installationg (Garmin GPS 175 maybe?), wondered if I could use the now-existing GPS antenna to feed the 175, then use the ESG as an "ES" and feed it w/ the 175 GPS signal. I queried Appareo (one of the input pins... 6 maybe?.. looked like it might be able to receive the GPS input signal) and they were very helfpul and replied quickly. Unfortunately, the answer indicated that the only difference between the ESG and ES boxes were in the firmware, but that they didn't have FAA approval to switch the firmware from ESG to ES to permit that change in configuration once installed... something like that. So, the answer was no. The ES can accept a GPS input from certain (but not all) GPS navigators. The ESG can not, nor can its GPS signal be used by other boxes. The interface kits for the Stratus ADSb-IN boxes (2, 3, etc) can be used with them to get GPS and adsb-in info to EFB apps, but I use a homebuilt Stratux for that.