Company Wants Me To Take Live Sales Calls As Part Of The Interview Process?

So wanted to get other people's thoughts since this is a weird one.

I've done 2 rounds of interviews with this place, nailed both interviews and I get an email today basically saying this.

As part of the interview process, we'd like to do a 3rd round of interviews where you would take live sales calls for 2 hours. I would be compensated if I close anything in those 2 hours but no hourly.

Its a legit company as far as I can tell, both interviews were by video and the people match with their LinkedIn profiles.

This isn't normal right? How can I take live sales calls when I know next to nothing about their company? This is a niche field where only a few people have prior experience in it, I'm one of the few. Even with that, I do not feel confident doing a live sales consult on a product or company I haven't been trained in. Doing 2 hours of work unpaid just stinks of a scam. Makes me wonder if they are offsetting hiring someone with a constant flow of applicants taking sales calls.

Thoughts?