Features: Duplex design: This product supports UHF and VHF frequency bands, enabling bidirectional communication and providing wide ranges of communication option. Modes: Support both Duplex modes and Simplexes modes, differencs in Duplex and Simplexes: in Duplex modes,have 2 time slot, and TX and RX can do simultaneously. Multi modes compatibility: The product supports multiple digital communication modes such as P25, DMR, YSF, etc., to meet the communication needs of different users. Built-in antenna: The product has a built-in antenna, reducing external connections and facilitating quick and convenient communication. Compatibility: Suitable for RPI ZeroW, 2W, 3B+, 4B, 4B+ and other versions, perfectly compatible for RPI platform. Specifications: Material: Printed Circuit Board Radio Frequency : in duplex modes,support uhf 430-440MHZ, in simplex modes support both uhf 430-440MHz and vhf 140-150MHz Best adjusted: TX=0, RX=0，need no offset. On-board LED to show status (TX, RX, PTT, Modes) Package Includes: 1x Duplex MMDVM Board 2x Pin Header note: Please allow 1-2cm errors due to manual measurement. Please allow for slight color differences due to different display resolution.