Blaylock Trailer (TL-33) Lock. The EZ Lock Model TL-33 Universal Coupler Lock is precision made of heavy grade aircraft aluminum and will not rust. It features a solid hardened 3/4″ steel locking rod, for use with large heavy duty padlock (padlock not included). Fits all trigger style: Fulton, Shelby, Dutton-Lainson, Atwood, and similar. Fits latch style: Atwood, Fulton cast couplers and similar. Does not fit Hammeblow (Bulldog) couplers. Inside dimension of the channel is 4-3/4 inches with overall dimensions of 4-1/2″ depth x 6-1/8″ wide x 5-1/2″ tall. A patented design ensures the most secure way to leave an unattended trailer.