GT20-TM Transom Mount DownVu 500W (CHIRP 455/800kHz) Traditional 500W (77/200 Hz) Transducer w/Temp - 4-Pin Width_3/8" - 4" You can see size differences

You can see size differences between bigger and smaller fish and even see individual fish swimming in bait balls

Hinge plate black RH top/LH bottom plastic

Screw hole to screw hole Dimensions: 16 3/4" W X 19 1/2" H X 2" D

and NO DRILLING

Use With Dometic RM2620 Refrigerator

GT20-TM Transom Mount DownVu 500W (CHIRP 455/800kHz) Traditional 500W (77/200 Hz) Transducer w/Temp - 4-Pin Width_3/8" - 4" You can see size differencesTransom Mount DownV 500W (CHIRP 455 800 kHz) Traditional 500 W (77 200 kHz) Transducer w Temp 4 Pin Get ultra clear sonar pictures of objects, structure and fish that pass below your boat with this all in one 4 pin transducer. This 20 ft transducer cable with built in fast response temperature sensor has a power rating of 500 W; a depth of 1,900 ft (traditional) and 750 ft (DownV); an operating frequency of 77 200 kHz (traditional) and 455 kHz