Hey Zach, Tardus is "investment agnostic." They don't recommend/aren't affiliated with a specific investment. You remain in control of your own money and do all of your own investing. Tardus is a coaching and education company that works with you to teach you to make smart investment decisions on your own, using the Income Snowball. The Income Snowball is just a method or strategy for investing.
There is a specific criteria required of the investments to make them work with the snowball, but they are investments that have been around for decades. The returns sound so high because one of the requirements is that the returns be principal and interest, not just interest.
Theres a number of different types of investments that fit the criteria, but we like to use peer to peer lending as an easy example;
Peer to Peer lending (on Prosper) - Invested $10,000 initially - receive $320/month for 3 years. $320 x 12 months = $3,849/$10,000 initial investment = 38% CoC Return
There's another thread on here where a lot of Tardus clients are giving their input as well; https://www.biggerpockets.com/...
(disclaimer, I work for Tardus in marketing, but I am not a coach)