The removable 1/2" tail allows more water flow through the filter and prevents cavitation from damaging the pump / pressure washer / cleaning system.

If a pressure washer pumps more than 15 litres per minute some suction filters will restrict the pump.
The beauty of the V-TUF universal suction filter is that it will fit 1/2 or 3/4 bore hose.
The 1/2 tail is removable so that if you need to fit it to 3/4 hose you can remove the 1/2 tail and open up the bore to the correct level.