Its cool and fairly functional but i can see why it is discontinued - Adaptive Tactical Venom Shotgun Box Magazine Conversion Kit, Mossberg 500 Series Shotguns

The finish, initial fit, and concept are all pretty great. I feel I got one of the last of the series and as such the quality of build may have been already slipping. Again, this conversion concept is well designed but the actual unit contains a lot of slop. Namely, the magazine does not adequately fit the receiver and this lack of tolerance prevents the receiver from contacting the shell release trigger on the magazine. As such, the mag fails to release a shell into the mag tube to be shoved into the chamber. Simply rocking the mag back and forth will eventually force the receiver edge to make contact with release trigger but I didnt get this device to spend time cradling a firearm. I have found that building up the outside surface of the receiver will mostly resolve the issue.
Luckily, I dont plan to use this piece very often so the clearly low durability components wont take enough abuse to fail. I am somewhere between disappointed and ok with what i got. 3.5/5