Extension Springs with Hook Ends are made of round wire and designed to absorb and store energy by creating a resistance to a pulling force. Extension Springs are available with different types of ends like threaded inserts, extended twist loops, cross loops, hooks, expanded eyes, reduced eyes, rectangular ends and teardrop-shaped ends. Extension Springs are mainly used in screen door retractor and circuit breaker. Extension Springs with Hook Ends find extensive applications in electrical, electronic, automobile industries etc.