Pen style laser pointer is perfect for slide presentsions, detailed discussions, microscope projections, field studies, and more. Provides a brilliant and highly visible (630-680 nm) red light with a 3.5mm beam diameter. Two AAAA batteries provide months of intermittent use or 2 hours of continuous use. Size is 1/2-inch diameter x 5-1/2 inches and weight is 1-3/8 ounces. Supplied complete with batteries and pocket clip. Replacement battery Cat. No. 291-1113.