This SportDOG Accessory Antenna measures 3".  It is a replacement antenna for the transmitter for SportDOG remote training systems.

Antenna fits: 

SportHunter SD-825

SportHunter SD-1225

SportHunter SD-1825

WetlandHunter SD-1825CAMO

UplandHunterSD-1875

Houndhunter SD-3225  

SportHunter SD-800 (transmitter version ST-120B only)

Innotek Field Pro Ranger & Scout (FP-RANGER, FP-SCOUT)

Package includes:

One 3 inch replacement transmitter antenna