I'm surprised that I wasn't caught with my mistake.
The three sizes aren't 1, 2 and 3, they're 1, 3 and 5. Number one is .45 mm, number 3 is .64 mm and number 5 is 1.06 mm. I've attached a pic of all three with the two different air caps (pictured on the right). You can identify each by the number of rings machined into each piece.The aircap on the right with no rings is used with the number 1 and 3 needle and tip. The number 5 aircap is for the number 5 needle and tip. I use the #5 most with pressure set to 20-25 pounds depending on what I'm shooting. I usually use the H for chassis and interior work and the Procon Boy PS-290 for bodies..