Mystery coax splitter

Hello - I need help identifying a 35-year old coax splitter in our basement. I inserted the image at the end of this post.

When I replace this splitter with a standard 2-way splitter, our TVs do not work. There is something unique about this splitter, but I can't figure it out. I'd like to buy a new one (in case this one dies), but I cannot find it anywhere on the internet. I wold like to learn more about this splitter. Thank you in advance for your help.

-Steve