[mirwa]

3/8 hose of any type is more than sufficient.

Some things to think about,

the longer the hose the more the pressure drop, so if your setting pressure at a regulator at the compressor then pressure at the gun will be different on a 6ft hose and 12ft hose.

The longer the hose the better as it allows air to cool from the compressor before it hits the spray gun and fluid.

Store the hose suspended so this way it does not collect dust from the floor.

Whenever your about to spray, wipe down the last 2-3ft of hose with wax and grease removed just like cleaning your guitar, minimises and reduces the dust.

My setup.

40cfm air compressor 415volt mounted on 200 litte air tank
Pressure regulator on the wall to filter and trap water and set pressure
20ft Air hose to a reciever tank 500litres (cools the air)
From the reciever tank another pressure regulator for the gun pressure
Air hose 12ft long suspended from the ceiling in the paint booth
Spray gun

Steve