This is a 20mm stack mountable VTX capable of outputting up to 800mW from Holybro.  It also does everything else you would expect from a VTX including tramp telemetry, LED indicators and a built in microphone.

Features:

• Compatible with all major FPV receivers from vendors such as Fatshark, ImmersionRC, etc.
• Supports the standard 40-channel set: band A, B, E, Fatshark, and Raceband.
• SmartAudio input allows remote control by the flight controller.
• Change channel, transmit power, and more from Betaflight OSD, flight controller USB port, Taranis Lua Script, and more.
• All parameters are controllable via push-button on the side of the unit, for cases where SmartAudio is not used.
• MMCX connector is durable and easy to use. Rated for 100’s of mating cycles. Easy and quick antenna changes. No more ripped-off UFL connectors.
• LED indicators for channel, band, and power. Allows easy check of vTX parameters simply by glancing at the quad.
• Variable transmit power from 25 mW to 800 mW. Use 25 mW for a race and then easily switch to 800 mW for freestyle.
• 0.5 mW True Pit Mode allows you to power up safely without the risk of knocking other pilots out of the air.
• Built in microphone, so you can listen to your motors while you fly, no matter how far away you fly.
• Standard 26mm form factor allows you to mount the Atlatl directly on your flight controller stack.

Specifications:

• Brand Name: Holybro
• Model: Atlatl HV micro V1.0
• Item Name:  5.8G 40CH 25/200/500/800mW Switchable FPV Transmitter
• Output Power: 0.5 mW (pit mode), 25 mW, 200 mW, 500 mW, 800 mW
• Audio: 6.5 MHz Mono
• Antenna Connector: MMCX
• Input Voltage: 7 to 21 volts (2-4S LiPo) with absolute maximum 30 volts
• Dimensions: 30x26x7mm
• Mounting Holes: Standard 20mm square to center of holes
• Weight: 3.6g

Resources:

• Holybro_Atlatl_HV_micro_Manual