A basin mixer is a type of faucet that combines both your hot and cold incoming water feeds into a single outlet, which is controlled either by a single knob or twin-hands to reach the desired volume of water at a specific temperature.  It is usually found in bathrooms, kitchens and laundry rooms.  While a faucet mixer taps a different combination of liquid at each outlet, a basin mixer taps both at the same time to achieve the most efficient use of water usage.