The Tank was made by Eureka Urethane industries, which as the name implies is a urethane company. They made one other ball and that was a red Budwieser urethane ball. The Tank had a pancake weight block to it, nothing fancy. Even though the ball came sanded it went real long and had a nice even roll to it. The major problem was that they were a urethane company and not a bowling ball company, and there were many problems with their cores and pours. Because of this we saw a lot of ball come out with voids/hollow spaces in them. They'd crack or you'd bang on the shell and hear the "echo" from the void underneath.