Yes, the Chapin Brass Adjustable Nozzle (#6-6000) can be used with the Chapin Industrial Viton Concrete Compressor Charged 3.5 Gallon Sprayer (1999).
The Chapin Brass Adjustable Nozzle (#6-6000) adjust from a cone stream pattern to a full pin stream pattern.
Yes, the Chapin Brass Adjustable Nozzle (#6-6000) will fit the Chapin Premier 2 Gallon Sprayer (#21220XP).
The Chapin Brass Adjustable Nozzle (#6-6000) adjust from a cone stream pattern to a full pin stream pattern. The cone pattern opens up but it is not the same as a fan spray, depending on which sprayer you have, you might be able to use the Chapin Brass Fan Spray Nozzle (#6-6001) instead.