Water flow rate bag is perfect product for measuring liters per minute usage of showerheads, basin taps and kitchen faucets. Very simple tool that will allow to tell if there is need of purchasing aerator to help saving money. To use simply place the bag under the shower head or aerators and turn on the water for 10 seconds. After that amount of time the lines on the bag will act as a liters per minute calculator (0-24 l/min lines).