The HHK A series provides an adjustable stroke of up to 1.2 m (3.9 ft) and up to 20%more efficiency than a traditional free-fall hammer of the same weight. The hammer is suitable for driving all types of piles: precast concrete, steel tube, sheet, and timber piles. The design of the hammer frame and drive cap makes for low impact noise and less vibration while piling. All impact energy is concentrated in the centre of the pile. The construction of the hammer makes it possible to use biodegradable hydraulic oils. The hammer is easy to connect to different hydraulic systems and can be operated either by the hydraulic system of the rig or by a separate power pack. Furthermore, it can be mounted on all kinds of leaders or be freely suspended.