to use tracking led lights, the combination is red and white. the ones used for tracking have 3 white led's and 1 red one. they are set about 3 inches from each other in a square pattern. it supposedly makes the blood 'blink'. i tried a blue one - don't waste your money. blue is good for looking into water. if i ever get a deer this year i'm going to try my white led flashlight with my red led headlight and see if it works.