This Aluminum Framed Swing Back Safety Tire comes with 4 sets of dual rare earth magnets embedded in PE Foam Tires and its covered in outdoor rated Polyester zippered cover. Great for backyard fun or serious dog agility training. This obstacle is Competitiion ready and has been featured Major North Amercian Competitions. Heights are pre-marked and easily changed by sliding each side up or down the upright and setting the locks.