Reduces the flow of warm water during showering up to 30%. Insert between the water tap and the hose towards the shower head. Costs less than one cent but can save hundreds of liters of warm water per year. Hardly any comfort reduction. Because of difference in water pressure, shower head and your personal comfort requirements, the design can be adjusted easily by changing the diameter of the center hole.
Just try it and remove it if you don't like it!
Not important PLA