You have to buy Traffic by the gallon, but sometimes you don’t need to use an entire gallon. That’s when it gets challenging, because then you have to figure out how much accelerator to use for whatever reduced portion of the gallon you need. How quickly can you calculate the volume of ¼ of a 1:10 ratio? Such a pain; we know. So,this handy mixing bottle has all these handy markings on the side for every possible fraction of a gallon you might want to mix up. Just pour the Traffic in to your chosen line, then top up with hardener to its appropriate line. No mess, no fuss.