There are multiple features to look out for when playing the Bank Vault slot. Firstly there is the Diamond Dollar Cash Prize, a scatter symbol which can pay up to 2,500x your bet on any spin.
The Diamond Dollar Cash Prize feature can also result from the Cash Wheel, which triggers one of three big features. Land three of the vault door scatter symbols anywhere on the reels, and the giant cash wheel will jump into life. There are two wheels at play here, one which picks your feature and another that adds a multiplier of 2x, 3x, or 4x to whatever you win from it.