New interesting and very expensive flahslight which replaces mag cap on Remington 870 shotguns. Good choice if you don’t have magazine extension. Haven’t tested it yet.

Remington 870 MK7 Shotgun Mag Tube Weapon Light by Steiner Optics

Remington 870 MK7 Shotgun Mag Tube Weapon Light by Steiner Optics

Manufacturer description:

The compact, ergonomic design of this 350-lumen mini-light makes it the perfect tactical shotgun light. A shotgun end cap attaches directly into the magazine tube and replaces the factory spring cap.

Integrated puch-button operation
Handheld or weapon-mounted capability
Recoil-resistant white light LED
Robust waterproof construction
High/Low Power Settings

Click here for more information

Gorilla Combat Flashlight

There is alternative product with similar features called Gorilla Combat Flashlight, it is sold for $112. Made in Thailand.

Gorilla Combat Flashlight for Remington 870

Gorilla Combat Flashlight for Remington 870

Gorilla Combat Flashlight for Remington 870

Gorilla Combat Flashlight for Remington 870

You can get more information on Remington 870 Forum.