RUSH TANK MINI 5.8GHz 48CH RaceBand 0/25/200/500/800mW Switchable FPV Transmitter VTX is great for mini fpv racing drones, with the 20x20mm mounting holes, it suites them perfectly.

Specifications:
Item Model: TANK Ultimate mini
Input Voltage: 7-36V
Output Voltage: 5V 1A
12V Input Current: 40mA@Pit mode, 95mA@25mW, 185mA@200mW, 250mA@500mW, 380mA@800mW
Channels: 48CH RaceBand / LowRace
Power: PIT/25/200/500/800 mW
Installation Hole: 20 x 20mm
Dimensions: 28 x 28 x 3.3 mm
Weight: 4.46g(without dust cover), 5.4g(with dust cover)

Support external audio

Package Included:
RUSH TANK MINI PIT/25/200/500/800MW 48CH Video Transmitter x 1