02. Here’s a comparison of my Springer’s stock 5-3/4-inch headlight compared to the 4-1/2-inch Martini light. Quite a difference not only in diameter but also in the housing size. The diameter of the front of the Martini light measures just less than 5 inches and about 3 1/2 inches from front to back. My stock headlight, on the other hand, measures about 6 1/2 inches in diameter and around 5 1/2 inches front to back.