Ping ISI BeCu. The aim of the ISI was to combine the look and feel of the famous Eye 2 - with the weighting features of the Zing 2. The Starburst cavity design improved feel by reducing vibration. With a thinner top-line and wider sole, this version is aimed at golfers looking for the advantages of a cavity back design with a more traditional feel. The beryllium copper (BeCu) heads are softer than the standard steel version. First launched in 1996 - ISIs are so popular you can still buy the standard steel version new from Ping.