That version of the Hammer was when it converted from a small-diameter disc to a large diameter mid. It was made in the early to mid 90's and advertised as "unbreakable" because it was molded with a very thick flightplate that won't easily crack. At the time, DX was the only plastic Innova made so an "unbreakable" DX was a good selling point.
Unfortunately, taking so much weight out of the rim and putting it in the center of the disc made the Hammer fly very slow, somewhat understable and all-around squirrely. As soon as the Millennium Aurora MS came out (a great stable mid that was basically unbreakable because of the better plastic it was made from) the Hammer went OOP. There was a brief attempt to bring it back as a floater (the "Hammerhead") but it didn't last.
