This is how you measure the corner pockets. Take the protractor measurement and place the legs on a ruler then measure the distance between the points of the legs, in this case the pocket opening from point to point measures 4 1/2" inches, yet the 2 balls set inside of the jaws of the pocket a little. The reason that happens is because in order to split the balls between the points of the pocket opening, the pocket would need to be measured at 4 7/16" because the balls don't touch at the points of the pocket, they touch below that point, which is actually wider than the measured distance of the pocket. So this pocket is actually 4 9/16" at the mouth of the pocket, a 1/16" wider than the measured pocket opening being 4 1/2".