This is a Yeti Thermoplastic prototype frame. Thermoplastic material was supposed to become the next greatest material in the 90'ies but it never seemed to take off besides GT who used the material successfully in their LTS and Lobo frames. IIRC there are a few thermoplastic prototypes made. I was going to buy the one that race driver Paul Tracy had but in the last second decided not to. I think the price given to me was 3500 dollars back in 1999.