Ping Eye 2 Beryllium Copper - The original Ping Eye 2's were great clubs, better than the later edition Eye 2 +'s.
At the time the featherlight craze was on, and Ping made a set called the EZ Lite, which were Eye 2's with the cavity scooped out. This made for an equally playable club, with a higer MOI.
When the lightweight experiment went into the trash heap, Ping was left with molds with nothing to do with them.
Ah....
If they could find a metal combo that would weight the same as the regular Ping heads, in the EZ Lite mold, they'd have something.
Beryllium Copper had been used before for limited edition putters, and would up being the exact weight with slight modifications.
Voila!
The greatest irons and wedges of all time.
No contest.