Help with identification and use of Bronica SQ prism

My first MF camera, a Bronica SQ-Ai, was purchased late last year from KEH. I have a lot to learn about it! Recently, I decided I wanted an eye-level prism, mostly to be able to focus accurately and compose at the same time (as opposed to using the spring-loaded diopter in the WLF), but also because it's nice to have a laterally correct image.

So I went back to KEH to see what they had. I couldn't afford a metered prism, but figured that wasn't a huge deal, as I could use another camera or an old Weston meter I got recently. I noticed that an AE prism with a "non-functioning meter" was listed cheaper than a non-AE prism, so I bought that. I guess I got lucky, because the prism I got seems to meter just fine! However, after being on the camera for a couple of weeks, it drained my batteries. I Googled, and found a few people talking about needing to turn the prism off when not in use. As far as I can see, there's no way to turn it off. There's just one big silver button which seems to activate the meter, and then a switch on the shutter speed dial, the purpose of which I cannot discern. I'd love to be able to find a manual for this prism, but I don't even know what it is. If anyone could point me to a manual, or at least give me the official name/model number of the prism that would be awesome.

Is there really a way to turn this thing off? It's not a huge deal to just remove it and store the camera with the WLF instead, but would be nice if I didn't have to. Thanks for any help you can give!