If you think you can play with Phil Mickelson's driver, then you're in luck: You'll soon be able to buy it from Callaway Golf.
Earlier in 2016, a driver labeled the Callaway Golf XR 16 Sub Zero (a great play of words on the video game "Mortal Kombat" and the color of the driver) showed up on the USGA's conforming drivers list, but there was little fanfare from the equipment maker. It seemed clear it was meant specifically for touring pros, and it turns out, Mickelson is one of those pros.
The story with this 440cc driver is that the company's engineers got together to design a version of the XR 16 with a center of gravity below the zero line, measured as the line running from the back of the driver perpendicular to the center of the club face. It's a first for Callaway, achieved in part with a new Carbon Triax Crown, which drives the weight center down.
There are also two interchangeable weights, 10g and 2g, in the head for customizing launch and spin, with the idea of killing spin as much as possible.
The Callaway Golf XR 16 Sub Zero driver will be available on Tax Day, April 15, with a $450 price tag.