Desk Top LED Light source. Great when you don't have a third hand to hold a flashlight! This is a very versatile little light. Can be used with pocket polariscope, pocket dark field loupe, or turn it on it's side to use with a refractometer. It is an LED, so don't use it with a spectroscope. It is 4" x 2.25" x 3" (to top of light) The light it's self is just under 1" in diameter.