Blackjack Strategy Video Source & Information:
The Wizard explains, demonstrates, and analyzes the 2-1-2 (aka Manhattan) betting system. Here is how to use it:
1. Start with two-unit bet.
2. Quit as soon as you lose a bet.
3. If you win first bet, drop to a one-unit bet.
4. If you win again, increase previous bet by one unit.
5. Go back to step 4.
More information: https://wizardofodds.com/gambling/2-1-2-manhattan-betting-system/