The position of the thumb relative to the rest of the fingers is also important in armwrestling. "Wrapping" your thumb is advantageous. It allows you to perform a more effective toproll, and it keeps your opponent guessing as to what move you will do (if you wrap your thumb every time). Additionally, sometimes it allows you to get higher on your opponent's thumb than would otherwise be possible. Look below to see pictures of a "wrapped" versus an "unwrapped" thumb.

In the picture at left, both wrestlers have chosen not to wrap their thumb. You can tell because you can see each man's thumb plainly. In the picture at right, you can see that the wrestler on the right has wrapped his thumb. Notice how his fingers cover his thumb. This is what it means to wrap the thumb. Notice also how you can see the first knuckle in his thumb if you look between his pointer and middle fingers.