Flusso 100.2715T Trim For Horizontal Thermostatic Valve with 2 Volume ControlsHandle Operation The middle handle is used to control the temperature of water flowing through the outlet. The left handle is capable of controlling the volume of water from full flow to a trickle for the output port 1. The right handle is capable of controlling the volume of water from full flow to a trickle for the output port 2. Cut Out Dimensions The cut out in wall should be 2. 08 X 12. 48 Inches and no more this will ensure that the trim plate