My 20-yard pin is green (for "You've got the green light; let 'er rip!); my 30-yard pin is yellow (for "let's take our time on this one and focus); and my 40-yarder is red (let's think about this one; are we sure there's not gonna be a better shot?). This is also the reverse order that the lights begin diminishing in brightness; I lose visibility of my red pin first, then my yellow, and -- last of all -- my green pin. When it's getting that dark, I don't need to be shooting at anything past 20 anyway until I finally lose enough light that it's time to pack it in.