Ping ISI Nickel. Ping's aim with these irons was to combine the accuracy of the Zing 2 model with the shot-making capability of the popular Eye 2. Ping's engineers achieved this goal through extreme perimeter weighting and a patented cavity design that has an ellipse and five vibration-absorbing 'starburst' design. A more rounded shape, a cleaner top line, and alignment markings on the face give the golfer confidence over the ball. The result is a club that feels solid, offers the playability that golfers need to control their shots, and is forgiving on mishits. This was the first ever club made from nickel. Astonishingly expensive when launched, Ping ISI nickels are rare. First launched in 1996 - ISIs are so popular you can still buy the standard steel version new from Ping.