This is a SOLARPEX MPPT Solar Charge Controller, Model MPPT 140D*, in grey with an LCD display and dual USB ports for phone charging. It is rated 12V/24V auto, 40A, with a max PV input voltage of 100V and max PV input power of 520W on 12V and 1040W on 24V. It uses MPPT technology to get more power from your solar panels, protects your battery from over-charging, over-discharging and short-circuit, and has clear terminals for solar panel, battery and load. Ideal for home solar systems, shops, and off-grid lighting and charging setups.