The CAMP Tricam offers protection in shallow pocketed placements. Occasionally that happens in granite but usually it occurs in limestone or other pocketed rock.
Tricams used to be more popular but they still have a strong, if not cult-like, following. I don't consider them mandatory for any Yosemite or sandstone routes, but climbers in more pocketed areas often swear by them. That said, usually a climbing cam with a flexible stem and narrow head will work in a Tricam placement. (Check out The Best Climbing Camming Device Review for a complete breakdown of the cams we tested).