The Simpson Strong-Tie piston plug delivery system for adhesives offers an easy-to-use, quick, and reliable solution for dispensing adhesive into drilled holes for threaded rod and rebar dowl installation in overhead, upwardly inclined, and horizontal orientations. The matched tolerance design between the piston plug and drilled hole virtually eliminates the formation of voids and air pockets during adhesive dispensing. This system is suitable for use with all Simpson Strong-Tie adhesives. It is made up of three components that include the piston plug, flexible extension tubing, and an adhesive retaining cap.