Garmin 010-10365-00 Fish Finder Speed/Temperature Sensor
Product Description:
Thru hull mount, plastic, temp & speed only.  
Works with the following fish finders:
Works with:

GSD™ 21
GSD™ 22
Fishfinder 90
Fishfinder 140
Fishfinder 160C
Fishfinder 300C
Fishfinder 400C
Fishfinder 100 Blue
Fishfinder 160 Blue
Fishfinder 240 Blue
Fishfinder 250
Fishfinder 250C
Fishfinder 320C
Fishfinder 340C
GPSMAP 420/420s
GPSMAP 421/421s
GPSMAP 430/430s
GPSMAP 431/431s
GPSMAP 440/440s
GPSMAP 441/441s
GPSMAP 520/520s
GPSMAP 521/521s
GPSMAP 525/525s
GPSMAP 526/526s
GPSMAP 530/530s
GPSMAP 531/531s
GPSMAP 535/535s
GPSMAP 540/540s
GPSMAP 541/541s
GPSMAP 545/545s
GPSMAP 188/188C Sounder
GPSMAP 198C Sounder
GPSMAP 235 Sounder
GPSMAP 238 Sounder
GPSMAP 178 Sounder
GPSMAP 178C Sounder
GPSMAP 398C Sounder
GPSMAP 498 Sounder
GPSMAP 298 Sounder