"The Evnroll lineup also has added a third grip as a user-friendly approach to the increasingly popular armlock style of putting, called the Midlock Grip. Rife’s assessment of many armlock style putters is that the standard putter grip—even wider-diameter options—encourages a severely delofted motion by forcing an exaggerated forward press, That setup requires armlock putters to have upwards of seven degrees of loft. Rather than forcing such a drastic loft change in a putter, Rife designed the grip by taking the most extreme version of the pistol-style grip and turning it sideways. Paired with the long slant style hosel, the Midlock naturally sets the putter in a typical forward press position and allows the putter to remain with a more traditional 4-degree loft angle."
Golf Digest