TRS-25 Question

[bpbowhunter]

I'm new to turkey hunting and am looking at purchasing a scope style sight. The TRS-25 gets very good reviews and is right in my price range but I have a question. My gun is a 870 express super mag and my question is how do you mount this style of sight to your shotgun. Sorry if this seems like a crazy question, just looking for a little advice.

Thanks,

Brian