Flusso Faucets Serie 160 Trim for Thermostatic Valve in Brushed Nickel (160.4000TBN)Handle Operation The bottom handle is used to set the temperature. The top handle is used for water diversion and volume control. Cut Out Dimensions The cut out in wall should be 6. 49 X 4. 44 Inches and no more this will ensure that the trim plate will cover the cut out hole in the wall. Trims The trims comprise of a well finished cover plate and handle knobs constructed in solid Brass. Over the temperature control knob, is an anti scald temperature