The SIMCom SIM66MD is a high-performance dual-band GNSS module supporting L1 and L5 frequencies for GPS, GLONASS, BeiDou, Galileo, QZSS, and NAVIC systems, offering exceptional positioning accuracy and fast TTFF with low power consumption. Housed in a compact 10.1 × 9.7 × 2.4 mm LCC package, it integrates a low-noise amplifier, supports AGNSS, PPS, DGPS (RTCM), and optional RTK for centimetre-level precision. Featuring UART, SPI, and I2C interfaces, the SIM66MD delivers up to 10 Hz update rates, −165 dBm tracking sensitivity, and operation over −40 °C to +85 °C, making it ideal for industrial, automotive, and IoT positioning applications. RTK version.