Ping I-Series Craz-E Putter. The I-Series range of Ping putters upgrades the tried and trusted designs with a new insert to ally a new feel with their proven weighting properties. This has resulted in the creation of the i-Series putters. The two-piece insert combines a urethane insert and face applique to produce a firm response with a soft feel.The thicker urethane insert provides the firmness required for a solid response. The thin, applique ensures a soft feel.