Feature: 1. UPGRADE COMMAND INFORMATION: If the board does not work in duplex mode, run the upgrade command of sudo pistar‑mmdvmhshatflash hs_dual_hat 2. HIGH PERFORMANCE: The MMDVM duplex hotspot module come with a 32 bit ARM processor with up to 10mW RF power, and each chip is thoroughly tested 3. COMPATIBLE MODEL: Can be installed on the current for Pi Zero, not compatible with 4. Supports for DMR, for P 25, for D Star, and for Fusion System 4. TECHNICAL PARAMETERS: The dual hat hotspot module operate at UHF 433‑900MHz and VHF 144‑220 MHZ. Modem selection when TX=0, RX=0: In the for Pi Star configuration, make sure the display type field at the top of the page is Organic LED type 3 and set the port to modem. Also, in the Expert section, go to the MMDVM host and scroll down to the Organic LED section. Make sure for LogoScreensaver is set to 1. Otherwise, the screen will go blank when idle 5. SIMPLE OPERATION: Duplex hotspot module firmware is pre installed and can be easily upgraded through software. On board LED light display status(Tx, Rx, mode) Specification: Item Type: MMDVM Duplex Hotspot Module Modem Select: For STM32_HS_GPIO Frequency Setting: TX, RX. Package List: 1 x MMDVM Duplex Hotspot Module 2 x Antenna 2 x Pin Header