What's inside? Titleist Brand Ambassador Gary Woodland's new Prototype MB irons.

A little further down the range, Titleist Brand Ambassador Ryuji Imada tests his new Prototype CB irons.

Ryuji's previous set of MB irons takes a breather.

Titleist Brand Ambassador Marc Leishman cleans the grooves in his new Prototype MB 9-iron.

Marc plays a mixed set of Titleist AP2 and MB irons.

The moment just after impact...

Here's a closer look.

This new Prototype MB iron belongs too... (Note the custom-stamped "C") ... Titleist Brand Ambassador Charley Hoffman.

The Titleist Tour Van has pulled out of Aronimink, but stay tuned tomorrow for more updates.

Here's what they look like in the bag.