Viewed from the playing position, the new grooves required on the professional golf tours this year are barely distinguishable from the old ones, which stopped being legal, or "conforming," on Dec. 31.

If you pull a new-groove clubhead up to your nose for closer inspection, however, you can see that the groove edges are a bit more rounded. The volume of the grooves is also about 40% smaller, which means that less grass and moisture will be channeled away when grass comes between the ball and the clubface at impact.