Golf Club Components: Clubhead Topline
The topline is the area on irons just above the face. It’s most pronounced at address. The thickness of the topline is widely considered a good indication of whether the club is designed for forgiveness or for workability, the latter of which is more popular with low-handicap players. The thickness is way for golf club engineers to place additional weight around the clubface perimeter, supposedly creating greater moment of inertia (MOI) or less twisting at impact with the ball for more centered shots.