Rapala Fish Scales. Catch fish scale Rapala Simply place it on the mouth or jaw of the fish and pull up. The precision of the materials allows the operation to be simple. These Lock'n Weigh Rapala trappers make the act of removing and documenting large catches a comfortable and possible situation to be carried out with one hand. Once the fish is near the boat, slide the fish catcher into the fish's mouth and pull up. The cam-lock locking system will make you raise the prey easily.