The TaylorMade Spider SR Putter is engineered with a premium, multi-material construction. The putter's heavy cast-in steel sole weights, tungsten/steel back weights and lightweight aluminum body combine to produce maximum MOI, forgiveness and stability. Taylormade's White TPU Pure Roll insert perfectly complements the Spider SR's multi-material construction. The Pure Roll's 45 degree grooves create optimal forward roll, an essential characteristic of "tracking" putts that find their way to the bottom of the cup.