Every component of these locking connectors are built to offer the lowest installed cost and maximum durability. Quick-threaded assembly screws install four times faster than cmpetitive products and backed-out screws come ready to wire. Rugged easy-to-grip nylon housing, clear thermoplastic terminal chambers as well as high-strength brass alloy contacts are all features of this premium Turnlok L1520C 4-Wire 20A 3-Phase 250V connector.