tension spring
8.Designs especially may fold the spring mattress, softness extremely good, the elastic force is extra-heavy, six links springs,cause the human body vertebra and the spring structure by the horizontal material parallel arrangement, helps the spring to comply with human body each kind of does produces parallel returns to the tension, may maintain in the sleep the human body vertebra level to delay the posture, protects your vertebra, stores up your health.
9.The mousetrap must contain a solid base to attach the four other parts to, a hammer that clamps down on the mouse, a spring which gives the hammer the necessary power, a holding bar which holds the now energized hammer in position, and a catch to which the holding bar is secured, holding the hammer in coiled tension.

