The primary difference between Aero and Mercury is where you can order them from.

• Mercury devices are available directly from Alarm.com.
• Aero devices are available only through distribution.

Another difference is the amount of expansions you can wire to a single controller.

• Mercury brand MP1501 supports up to 8 additional expansions (17 doors).
• Mercury brand MP1502 supports up to 16 additional expansions (32 doors).
• Aero brand X1100 supports up to 32 additional expansions (64 doors).