To discern HB GPS antennas...

Some have a gray gasket between the top and bottom housings and by the printing on the top housing...

GR4/GR4RD GPS Receivers were welded and have no gasket. They should state “ADVANCED ACCESSORY SYSTEM” under the “HUMMINBIRD”.

The GR16, GR50, GRHA, GRP, and GR-HS all look similar but have different artwork on the top of the housing. They have a Dark Gray gasket visible between the top and bottom housings.
* GR16 states: “GPS ACCESSORY SYSTEM” under the “HUMMINBIRD”.
* GR50 states: “AS-GR50 GPS MODULE” under the “HUMMINBIRD”.
* GRHA states: “AS-GRHA HIGH ACCURACY GPS” under the “HUMMINBIRD”.
* GRP states: “PRECISION GPS MODULE” under the “HUMMINBIRD”.
* GPS-HS states: “AS-GPS HS PRECISION GPS + COMPASS” under the “HUMMINBIRD”.