The instrument consists of a circular base with two vertical guides. The hammer of weight 13.75 �0.25 kg can be raised to fall freely down the vertical guides. The height of fall can be adjusted through 380 � 5mm. The hammer is provided with a locking arrangement. The hammer falls freely to the base and is removable for emptying. Supplied complete with metal measures 75mm dia x 50mm high (for specimen preperation) and tamping rod 230mm long x 10mm dia.