Before SkyBox released its revolutionary 1990 product — one of the most futuristic card designs of its era — the company distributed prototype samples to introduce dealers and collectors to what was coming. These prototypes were sent inside mailers and boxes, stamped with the word PROTOTYPE across the front, and most were discarded without a second thought. Only 537 have ever been submitted to PSA, and just 8 have received a PSA 10. With only 3 recorded public sales, the market for this card is genuinely thin — which cuts both ways. It means the price discovery is limited, but it also means that when one does surface in gem mint condition, it commands serious attention.