1/2" Part 1 High Pressure Brass Float Valve

what's the difference between a part one and part 2 ballcock pls

Is this a standard replacement arm for a traditional standard cistern please ? Thanks.

is this a quieter type of ball cock system, one where water noise on exit is less is less and

Part no vdtaz012 is32.4 the length of the flout arm ( 1/2 ins long arm float valve)