LF-4 
The LF-4 transmitter is one of our most popular options for its high output power and longer battery life. This transmitter features low battery warning, magnetic on/off and a short 6.5 inch (16.5 cm) antenna without sacrificing performance.  Weight: 7.5 grams Battery Life: 10 days plus an additional 3 days in low battery mode (over 300 hours total)Range: 30+ miles