This is a clone of a Remington 870. So it will accept after market 870 parts, so you can customize it exactly the way you want. There are different stocks, and forends (Rackers) some that let you mount lights, some have lights or lazers built in.

Joe, it means this shotgun is a virtual clone of the Remington 870 shotgun physically and will accept the same popular furniture, stocks, fore-ends etc of the 870. Cheers and stay safe!

It means it can accept Remington 870 parts like stocks, pump grip, magazine tube and probably barrels. Hope this helps