Sell two ATM put options, buy one ITM put option and buy one OTM put option.
The Max Loss is limited to the ATM strike less the ITM strike less the net premium paid for the spread.
The Max Gain is limited to the net premium received from the spread.
When to use: When you are neutral on market direction and bearish on volatility.
This strategy is the same as the Long Call Butterfly except we use put options instead of call options.
A Long Put Butterfly is used with similar intentions to the Short Straddle - except your losses are limited if the market moves out of your favour. Whereas a Short Straddle has unlimited losses if the market moves.