The NN-21-BR is a nickel-plated brass locking nut used to secure strain relief fittings. It features a 3/4” NPT thread, a thickness of 0.14 inches (3.5 mm), and requires a wrench with 1.18-inch (30 mm) flats for installation. As a durable accessory for strain relief systems, this locking nut ensures a secure and stable connection in various industrial applications.