AP-1 prepares surfaces accelerates curing and promotes maximum performance of Park Tool TLR-1 and TLR-2 Threadlockers as well as RC-1 Retaining Compound. Conveniently contained in a pen for easy and precise application.10ml penCompetes with Loctite 7649NOTICE: When retaining compound or threadlocker is used on carbon fiber frames or components adhesive primer must first be applied to all component fastener and frame surfaces. Failure to do so could result in permanently bonded parts.CAUTION: Some painted surfaces can be sensitive to threadlockers retaining compounds and primers. Test first on an inconspicuous area to see if it causes a stain or discoloration. Clean off any excess from painted surfaces immediately.