Even if he doesn't see you, you can see him. Clip to vest or belt, or use magnet base. Stick the magnet base onto a car coupler for high-visibility warning that car is being worked. 

Uses single “D” cell battery. Height 4.5" tall.  Belt Clip and magnet base.

Xenon flash tube. Blue light is also available with an LED bulb, which offers even greater brilliance and reduced battery drag.

Weight: 1.5 lbs.