It is a closed-spring mount with excellent anti-vibration effects. Because the spring is not exposed to the outside, it is corrosion-resistant and it has a gauge at the center to help check deflection. The top and bottom housings are made of P O LYCA R B O N AT E plastic, w hich is st able regardless of load and strength, and anti-friction inside the housing reduces structure-borne noise. Plus, the anti-vibration neoprene pad on the top and bottom contact surfaces prevents structure-born noise from getting transferred to the base of the equipment when it is in contact with STEEL and concrete.