The left or right size refers to the orientation of the obstacle. To put it simply, if you are left handed, go with left, and do the opposite if you are right handed. The "Hole" refers to the hole in the fence. Foul Fingers hand crafts quality cement fingerboard obstacles in Colorado. Realism is an important part of any fingerboard set up, and nothing is more real than cement obstacles like the ones you would be hitting in the streets!