antoniop: Thanks again, you're all over this forum.
BTW, the Tower price is $11.99 for 3 seems kind of steep.
I found at a local Art Supply Store, a set of 3 for $5.95. The difference is that these are made by Createx. They have a plastic cap to cover the bottle when not in use, and the cap is plastic like the original Fastcolor cap.. Apparently, the bottles that Parma uses for the FastColor paints is the same bottle as the Createx brand of airbrush supplies.
Allows artist to use Createx bottles as airbrush jar. Simply screw bottle adapter on and plug into airbrush. Saves time and money. For use with all suction feed airbrushes. Fits 2 and 4 oz Createx airbrush bottles. 3, 6, & 12 pack assortments available.