Rife IMO Putters. Introducing the Rife IMO Putter. A new weighting innovation from Rife Putters. We"ve positioned 85% of the putter head"s mass directly inline behind the ball giving the IMO very high MOI and incredible stability. This makes swinging on plane automatic. No pulls. No pushes. Just dead straight. All aluminum putter head with 85% of the total mass concentrated in the middle 40% from a front to rear direction. The sides are hollowed out underneath and only represent the remaining 15% of the heads mass. The USGA requires that a putter must be longer from a heel toe direction than from front to back. The IMO is right under this limitation, measuring 4.75" wide and 4.60" deep. By concentrating mass in the center of the putter, a golfer will naturally swing on plane