in shaft 12 and selectively engages with engagement surfaces 24 a 24 b when the user rotates lever 20 the lever 20 pushes on rod 26 causing rod 26 to slide toward the distal end of shaft 12 to operate the spray device assembly as described below the handle assembly 14 includes a mode control knob 28 that dictates the amount of longitudinal movement the rod 26 experiences as the user rotates lever 20 through its full range of motion and thus dictates the volume of liquid sprayed during a single operation of the lever specifically the mode control knob 28 controls the position of engagement of the rod 26 on the lever 20 i e which concave engagement surface 24 a 24 b is engaged with rod 26 the mode control knob 28 has a cam surface 30 that engages with the side surface of rod 26 when the control knob 28 is rotated the cam surface transversely moves the proximal end of rod 26 between engagement surface 24 a and engagement surface 24 b with the mode control knob 28 rotated to its low spray volume position see fig2 b 3 b 5 a 5 b the proximal end of the rod 26 is positioned on engagement surface 24 a which is closer to pivot point 22 and thus results in a smaller longitudinal displacement of the rod 26 for a smaller volume of spray as the lever 20 is moved through its range of motion with the mode control knob 28 rotated.