Spectrometer Spectrophotometer Prism ?

Description

Spectrometer Spectrophotometer Prism ?
The inside is hollow but has a mirrored lens of some sort. It measures approx. 7" across and weighs 3lbs 9oz.
If anyone could confirm that this is a prism or what it is, I'd appreciate it. Thank you!
See pics for condition. Nothing else included. Sold as is, no returns.
NOTE: Please don't let my low feedback score discourage you from purchasing this item. This eBay user id is a new account which I started, after converting my previous user id to "BarnoneSurplus" Please feel free to message BarnoneSurplus to confirm this. Buy with confidence that you will get the same level of service from BentleysBarkinBox, as you would with "BarnoneSurplus".