It removes air from the break, fills it with durable resin and makes it even stronger than before. For best results, repairs should be made as soon as possible after the damage occurs and before the break is contaminated by dirt or water. The kit works best on round damage not more than one inch in diameter and cracks not longer than 12 inches. Easy to use and operate Quick repair in 20 minutes Repairs various types of damages caused by traffic accidents, collisions