Garmin 010-10253-00 Transducer Mounting Bracket
Product Description
Suction cup transducer adapter. Using your GARMIN fishfinder as a portable unit? You'll need
this adapter, which allows you to stick a transom mount transducer to the side of a boat.
Works with:

GPS 125 Sounder
GSD™ 21
GSD™ 22
Works with the following fish finders:
Fishfinder 90
Fishfinder 140
Fishfinder 160C
Fishfinder 100
Fishfinder 160
Fishfinder 240
Fishfinder 340C
GPSMAP 420/420s
GPSMAP 421/421s
GPSMAP 520/520s
GPSMAP 521/521s
GPSMAP 525/525s
GPSMAP 526/526s
GPSMAP 135 Sounder
GPSMAP 168 Sounder