Park Tool AP-1 Adhesive Primer - 10ml PenPark Tool AP 1 Adhesive Primer 10ml Pen. 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 pen Competes with Loctite 7649 NOTICE: When retaining compound or threadlocker is used on carbon fiber frames or components adhesive primer must first be applied to all component fastener