It allows me to put both lines down as a pair and maintain a constant distance. The black lines represent the pinstripe color and the white is the background color. You simply put down the lines and then paint between them. The lines are flexible and can be bent to make corners. If you're sloppy then you extend the outer edges with making tape. Kind of like the paint between the lines coloring books they had years ago. Yep, I'm gona need the masking tape because I always screwed them up when I was a kid.
What I don't know is the approximate width of the color lines and the center spacing between them. The one above is 5/32, 1/8, 1/16" but I don't want to order it till I confirm that it's close. The stencils are called The STRIPPER". They come in 42' rolls, cost about $10.00 and are made by Finesse. Here's a link to the design options available: TCPGlobal.com Sripper Tape. The one I was looking at is design FNE F-2.
Don't need it to be exact... Just looking for something close to stock.