This is a 144-LED intensity adjustable ring light for stereo microscopes with mounting size 2.4" (61mm) in diameter. The ring light has 2.4" (61mm) inside and 4" (100mm) overall outside diameters. It works with power supplies from a 100-240V and comes with a 1-7/8" (48 mm in diameter) ring adapter. With variable intensity control, it provides cool, even, intense and focused shadow-free illumination. It is an ideal durable cool light source for all stereo microscopes. This kit comes with one year warranty against manufacturing defects. It is brand new in original box. Its retail value is $320. Features & Specifications : 144 bright white LED bulbs Lighting direction changeable Variable intensity control Intense and focused shadow-free illumination 100,000 hours of life Power input: 100-240V, 50-60HZ, auto switching Fits up to 2.4" (61mm) mount rings Inside diameter of the ring light: 2.4" (61mm) Overall outside diameter: 4" (100mm) Packing List : One 144-LED Ring Light One Power Adapter One 48mm Ring Adapter Shipping Weight: 1 lbs