Internally-fed power rollers

These power paint rollers have perforated covers with the paint fed inside the cover and distributed along the inside length, before coming out through the holes distributed over its entire surface.  The roller head is usually mounted on a heavy duty extension pole which is airless pressure rated so that it can be safely connected to an airless paint pump and the flow controlled by an airless gun at the other end of the pole, usually of the in-line type which is much more comfortable than a standard airless gun would be.  You should be careful not to connect a telescopic roller pole that has a low pressure rating and designed for a low pressure system.  The roller covers usually have the American 1.5" internal diameter, and are available in several nap lengths to suit the work.  Some have a foam layer between the core and the nap to better handle very rough surfaces