The OEM Automotive Tools Ultra-Violet Light Pen, No. 24610, is used to help find leaks in A/C systems. The LED produces a high-intensity, ultraviolet light to detect fluorescent dyes. The Ultra-Violet Light Pen fits easily into a user's pocket. It is made of lightweight aluminum with a pocket clip for convenience and accessibility. This light features a high-impact lens to resist breakage, a one-hand push on/off button, 4.5 hours maximum run-time and is water resistant. It comes with two AAA Duralast batteries.