Under this strategy there are more long call positions than short positions and the credit received from selling calls is used in ratio to buy long call positions.
Profit Assumptions: This strategy is if the assumption is bullish. However if the market goes against the assumption the trader still makes profit as being a credit spread the premium received is generally more than the premium paid.
Example: Considering the market trading at 5000 sell 1 4800 call option and buy 5200 two call options. Book profits in 4800 call if market goes down and you automatically make good profits if market goes up
Risks: This is the strategy which is a safe strategy with low risk and unlimited profit if market goes in your favor.