Callaway Women's Big Bertha Driver Hyper Speed Face: Our New Hyper Speed face design is nothing short of groundbreaking Adjustable Perimeter Weighting Forged Composite: High Strength, Lightweight crown saves 20g of weight, allowing Big Bertha to have Adjustable Perimeter Weighting Advanced Adjustable Hosel: Increase or decrease loft in 1Degree increments (up to +2Degree or down -1Degree) with the adjustable hosel