Here’s how the trade works. The historical volatility in August Gold Futures on a 30 and 60 day basis is approximately 11.75%. The implied volatility of the $1600 Call, however, is 17.75%. We’re going to Buy one $1550 Call with an implied volatility of 16.80% while selling two of the $1600 Calls. This provides us with the opportunity to establish a short delta position of approximately .14. In addition, we get short a bit of vega and hopefully can take advantage of the implied/historical volatility difference. The details are in the Table [in the article itself].The trade leaves an $8.80 credit in the account using his figures, and has a maximum profit of $58.80. He suggests calling him for questions on how to implement it.
The strategy might be worth updating with current figures. Sadly, given gold's recent stumbles, the premiums of the $1,600 calls to be sold have likely shrunk relative to the $1,550 call to be bought - but that doesn't mean it isn't profitable still.