Wobble-Fix refers to the section of the extension bar that holds the socket. Specifically, in reference to the flexibility of movement that a socket has when attached to an extension bar with this feature. Wobble-Fix extension bars offer two different secure solutions for holding a socket in place. 
 

The “Fix” solution holds the socket securely and steadily on the extension bar permitting no movement. The “Wobble” solution permits movement of up to a 15 degree angle