Ping have developed an iphone Application and cradle to hold on the putter shaft.
The purpose of iPING Fit is to identify the golfer’s stroke type – straight, slight arc, or strong arc – and then match the player with the PING putter models that fit their stroke type, the key to improved consistency on the greens. Classifying PING models by their face angle and corresponding stroke type is a new putter-fitting approach the company calls Fit for Stroke. Every putter head is either face-balanced for a straight stroke, mid-hang for a slight arc, or toe-down for a strong arc. To make identifying a putter easier, every model has a shaft label that is color coded for stroke type: blue for a straight stroke, green for slight arc, and red for strong arc.