Features and Application:: For Wood and Plastics vary from communication equipment, the automotive industry, computer industry, and anywhere where strong durable threads are required in wood and plastics. Brass Tappex Type Inserts Brass Molding Inserts Brass Inserts Plastic Molding inserts are used with plastics and soft woods. They are available with serrated grooves and are push fit type. Available unheaded, headed and reverse headed. Imperial thread sizes and studded versions also available.