Xtra Bond Additive is a windshield repair resin additive that will increase the adhesive bond to the glass of any resin. Xtra Bond does what is a fundamental process of almost all adhesive applications and that is preparing the surface to be bonded, which was never available for windshield repair before this invention. Add 1 drop to 4-5 drops of resin into your injector and stir with a toothpick. Then do the repair. The Xtra Bond will etch the glass and increase the molecular crosslinkage to the glass. One bottle will do 60 stone-breaks. Recommended for Stars and Combination breaks in the defroster area.