TBS has built the smallest VTx, with Unify Pro pedigree and newly-revised u.FL connector. Comes with Smart Audio support. You will be blown away with the performance in terms of range, signal clarity and signal spacing.

Input Voltage: 4.5V - 5V
Power levels: 25mW / 50mW
Interface: SmartAudio and capacitive button (or solder external tactile button separately - included!)
Weight: 1.4g (incl. antenna)
Size: 13.2mm x 14.6mm
Antenna connector: u.FL (upgraded)
Antenna length: 45.6mm (end to end)
TBS Tech: Smart Audio, Clean Switch