The Tug-Preventing Dog Trainer.

"This ultrasonic device trains dogs to walk without tugging their owner. The device attaches between the leash and collar (neither included) and when the dog tugs, the integrated speaker emits a harmless ultrasonic tone that canines find irritating yet is inaudible to humans. The dog associates the unpleasant sound with pulling on the leash, thereby learning to walk properly. The speaker can be directed into the leashed pets ear so as to not disturb other pets and the four volume levels can be adjusted manually to accommodate dogs with different levels of sensitivity. Compatible with any leash and suitable for all dog breeds and sizes. Requires two AAA batteries. 6 1/2"" L x 1 1/2"" W x 1"" D. (4 oz.)"

The The Tug-Preventing Dog Trainer. from the Gift Guide>Under $50 is made by and can be purchased online via a secure server from Hammacher Schlemmer.