The Transfer Cap is designed to let you spray paint from the can onto a pallet or a dish so that a paintbrush can be used. When not used in this manner it is very similar to the Needle cap and produces a line that is .6 inches wide and can shoot higher than regular caps. While this cap still has all the benefits of the Needle Cap, the longer straw allows you to make a "Mixer Cap". By putting this cap on both ends of the straw it allows you to "transfer" paint from one can to another, effectively allowing you to mix any color. Super handy for utilizing leftover half empties and developing color theory. Note: This trick will not work unless one, and only one, of the cans is frozen . When contents under pressure becomes freezing temperature, it creates a vacuum. The frozen can takes the unfrozen can into it.