Head-Lites' patent pending LED light insert is available as an add on to your Head-Lites collar for a different coloured light to be swapped in! Light insert sizes correspond to your collar size - not sure what size to order? Drop us a line! The number of LEDs on your current light strand also indicate the size you have: Low Beams 10-12" collars have 10 LEDs Low Beams 12-14" collars have 11 LEDs Low Beams 14-16" collars have 13 LEDs 14-16" collars have 12 LEDs, with an angled light joint 16-18" (Cani-X 15-17") collars have 12 LEDs 18-20" (Cani-X 17-19") collars have 15 LEDs 20-22" (Cani-X 19-21") collars have 18 LEDs 22-24" (Cani-X 21-31") collars have 21 LEDs 24-26" (Cani-X 23-25") collars have 24 LEDs