This popular Fluidmaster toilet inlet or fill valve in black and red is the 400 model range which is the go to valve for plumbers around Australia. It has a brass 1/2" BSP thread on the bottom which measures approx 21mm diameter. Height adjustment is by simply twisting. Fine adjustment can be made with the screw on top. Water level should be no less than 25mm below the top of the overflow tube. It comes with plastic nut and seal on the bottom.