Mullican 26504 78″ x 2″ Engineered Hardwood Nail Down Hardwood Flooring End Cap/Threshold. Mullican 26178 Castillian Premier 78″ x 3/4″ Engineered Hardwood – Boardwalk. Mullican 26177 Castillian Premier 78″ x 3″ Engineered Hardwood – Boardwalk.