This Model Uses A 4w Uv Lamp To Check Documents Protected With Uv Sensitive Features. The Fl-90092 Is Also Impact Resistant And Small Enough To Fit In Your Briefcase Or Tool Box. Requires 4 aa Batteries. (not Included). Comes With Handy Wrist Strap. Long Bulb Is A Blacklight , , Can Be Used As A Regular Flashlight , , Measures 6.5 X 2.25 And Weighs Only 3 Oz