Gauge Design TransformerThe Gauge Design Transformer is a classic design mallet using the utility patented SPI technology. The Transformer includes two replaceable sole plates. The black body is milled from T6061 aluminum and the sole plate inserts are milled from 303 stainless steel. Both the body of the putter and the inserts have the brick sole milling. Head weight 360g 365g. This putter comes in both center shafted and heel shafted double bend.