An external mount transmitter attaches to the fish through the musculature on the mid-dorsal region of the back at the base of the dorsal fin. This design is intended for fish who would be damaged by implanting a transmitter and whose habitat does not contain weeds to entangle the transmitter. Using an external mount transmitter can affect the fish's balance. Good field range is obtained through the trailing whip antenna, and even better range will be realized if the enhanced range option (models with "B" suffix) is chosen.

Anterior and posterior attachment wires are embedded into potting.

Series	Weight (grams)	Life (days)	Description
F1905	0.6-1.3	20-122	Smallest sizes, reduced power output for longer life, minimum potting for lowest weight., silver oxide battery, flat rectangular shape. Limited frequency availability.
F1900	1.2-3.9	15-468	Small size, standard power output for normal life, normal potting for durability, silver oxide battery, flat rectangular shape.
F2000	8.0-33.0	161-2036	Cylindrical shape, lithium battery. Enhanced range option available.
F2100	12.0-29.0	146-1212	Rectangular shape, lithium battery. Enhanced range option available.