Which of the following is NOT part of traveling equipment for horses?

Traveling equipment for horses is specifically designed to ensure their safety and comfort during transport. The correct answer, helmets, are not considered part of the traveling equipment for horses; rather, they are part of rider safety gear.

Travel rugs, hock boots, and tail guards are all essential items used during the transportation of horses. A travel rug keeps the horse warm and comfortable, especially in colder conditions. Hock boots help to protect the horse's hocks from injury or bumps that can occur during travel, while tail guards prevent the tail from being damaged or dirty during transport.

Therefore, helmets, which are primarily used for the rider’s safety while riding or handling the horse, do not fall under the category of equipment specifically meant for the horse during travel.