Our easy to use product removes air from the break, fills it with a durable resin and make it even stronger The repair is almost invisible. Use only per package instructions Treatment after the crack has formed and prior to repair Works best on round damage not more than one inch in diameter and cracks not longer than 12 inch Will not repair damage to more than one lauer of glass Easy to use Fix and reduce breaks and minimize the appearance Advance resin forumla Full instructions given on manual which provides in package