Certified A/C Pro Automotive Air Conditioning UV Leak Detection Kit includes a professional grade, high-intensity true ultraviolet leak detection pen light that works with all types of UV leak detection dyes. Includes yellow tinted glasses and batteries. For detecting leaks in automotive air conditioning systems. Directions: Put batteries into the light by unscrewing light base. On/Off button is located on bottom of light. Add Ultraviolet Light dye to system being tested. Allow UV dye to circulate. Always wear UV safety glasses. Use light to check for leaks.