10 inch active driver with 10 inch passive. Low level/high-level speaker inputs. Adjust cross-over frequency 35 to 100 hertz. Bass level and phase adjustment. This is a well designed sub woofer and very serviceable. It's capable of taking over 2000 watt loads into 4ohms. We have upgraded the capacitors (checked for any off spec OEM caps and replaced with a better type/ more appropriate value). Certain capacitors can be had for less cost in bulk so manufacturers are often motivated to use capacitors that are close to spec, but not the ideal choice. We have also rugged-ized the internal components/ soldering of crucial parts. This sub will really shake things so it's important that things are nailed down!