We just got in the new Surefire DSF shotgun forend lights. These are 600 lumens of light output and replace your shot gun forend.
We have both the Remington 870 and Mossberg 500 590 versions
Surefire DSF-870 Shotgun light for Remington 870
Surefire DSF-500/590 Shotgun light for Mossberg 500 or 590