The unique two-sided design allows the screen to eliminate 99 Percent of splash back on both sides. This prevents incorrect installation which can result in a mess around the urinal. The Wave 3D makes it easy, simply place it over the drain in the urinal and youre done.The Wave 3D lasts the full advertised 30 days and then some. Only Fresh Products has a patented fragrance load that gives it 3X more fragrance than the closest competitor.The Wave 3D comes with reminder tabs along the top and bottom edges of the screen. Simply pull off the week tab and the month tab that corresponds to 30 days from installation. Now its easy to remember when to change out the screen.The Wave 3D contain billions of beneficial bacteria that consumes odors, so it doesnt just mask them. These amazing bacteria also help keep drains clean, clear, and smelling fresh.