During a recent speech at the Stanford Graduate School of Business, chairman of Apple's board Arthur D. Levinson said members of the board are typically presented with new products anywhere between six and 18 months before they are revealed to the general public.

Board members usually don't have much input with regards to new products but in the event that there is enough time before launch, opinions are sometimes taken into consideration. What's more, if a specific board member happens to have expertise in a particular field, their advice may be more influential.

As Levinson describes, it's not the board's job to define product specifications. Their job is to be a sounding board and serve as resource, not to get in the way of the CEO or the executive team. Ultimately, he said, the board's job is to hire and fire the CEO.

The chairman also addressed his role of running the board following the death of co-founder Steve Jobs. He said the experience has been weird and that he's still not to the point where he walks into the board room and doesn't miss Jobs. Levinson noted that Jobs was a one of a kind guy and that the Jobs the public knew was not the same Steve Jobs he knew.

Levinson became chairman of the board in November 2011 shortly after Steve Jobs passed away. The executive also serves as the chairman for Genentech, Inc. and is on the board of directors for Roche, a pharmaceutical firm.