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.

Here's a closer look.

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

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

Marni Ines of Titleist Golf Club R&D looks on during Gary's first testing session.

Ryuji games 4-9 MB irons with True Temper Dynamic Gold shafts.