1:1
Place a unit on any outside 1:1 bet (high/low, even/odd, red/black). Upon loss, double the bet. No matter how many progressions deep, 1 hit will always result in a full recovery PLUS 1 unit profit.
Variations:
Marty + (super martingale):
Upon loss, double + 1 base unit - 1,3,7,15, etc... No matter how many progressions deep, 1 hit will always result in a full recovery PLUS 1 unit of profit for EACH progression. This is my preferred progression.
CRITICAL WARNING:
Exponential growth is aggressive. A $1 base becomes $127 in just 6 steps. Use with extreme caution and high bankroll-to-unit ratios.
BET PLACEMENT