The Northrock 1.25 inch Steel Vibrator Head 25F12 provides a high level of centrifugal force and amplitude are created by rotating Northrocks unique eccentric weights within the head at the desired frequency. A special oil bath system keeps the weights lubricated at all times. All heads are sealed at the factory and are maintenance free. Built for the busy contractor and a wide range of tough rental applications they are designed for reliability and durability over extended periods of time.