- 1 Spray, 1.75 Gpm, Gray surface and exclusive GROHE DreamSpray technology that ensures a steady, even water flow from every nozzle. Featuring SpeedClean to easily wipe away limescale with your fingertip, the sleek, slim profile of the Rainshower Mono 310 brings contemporary style and superior performance to today's bathroom.310 Mono Shower Head, 12-in.