TechGrow Humi Heavy is a humidity controller built to drive powerful humidifiers and dehumidifiers in grow rooms. It works with an external Temp/RH probe to display humidity and air temperature on a 2×16 LCD, and switches automatically between humidifying and dehumidifying to hold a setpoint between 10% and 90% RH. A heavy‑duty 10‑amp relay handles high loads, while settings and hysteresis are retained after power loss. Status LEDs show activity. The unit operates on 100–240 V, 50/60 Hz, and includes a 5 m UTP cable and mounting kit; the Temp/RH sensor is sold separately. Compatible TechGrow sensors include S‑4 (2,000 and 10,000 ppm). Product dimensions are 18 × 7 × 13 cm; weight approximately 765 g.