This mount is actually very good to mount a small weapons light to the 870 for general light duty. I have it mounted under the extended magazine tube. There, it is a little difficult to operate because I have to remove my hand from the fore end to get to the switch.
I tried mounting it to the side for ease of access, but found that it sticks out quite a ways and was afraid I'd break it off under hard use.
However if you don't want a light integral to the fore end, it is a reasonable compromise for average home defense use.
It is not 'cop proof', IMO.
Pros: Easy to mount. Inexpensive
Cons: Too flimsy. Sticks out too far. Light is left too exposed
This review was written in the old system and had content requirements that are different than reviews written today.