This is a EC-bet, played with 2 ECs.
consider these two pairs/groups
RED HIGH<>BLACK LOW
RED LOW<>BLACK HIGH
(These pairs are also located on the same side of the wheel).
Trigger: When one of the pair within the group hit twice without the other pair being hit, bet the opposite pair with 2 ECs. (For an example RED HIGH has hit twice without BLACK LOW being hit, then bet BLACK & LOW EC).
Progression: double bets for each loss. This work pretty well, most i've seen is about 9 repeats within the same pair, so it Should cover most losses before reaching stoploss.
Bankroll: 100u playing with 1u bets, 500u playing with 5u bets.
4/4 Games won
As you can see in these charts, drawdowns didn't come even close to stoploss (-500u) at an extreme level of "bad luck" 7-8 Repeats of the same pair, this is an extreme event, although it didn't destroy our bankroll.
What is more, the reason why i like this bet is because it's played with 27 numbers, but in reality it's a 50/50 bet.
(Fist tests was played with 5u bets)