XIANQI High quality premium metal, heat treatment process, high hardness and toughness. Wedges and pen wedges for hand splitting of stone, rock, granite, marble, concrete. Take care before use and take the necessary precautions; stay alert when the stone is about to split . 5/8" (16 mm) diameter, using a 1/2" hammer head. The concept of these devices is that they split rock by applying them from the inside out. These wedges are small but can exert an amazing amount of force Package includes: 10 piece stone spreader Specifications. Material: metal Overall length: 10.5 cm / 4.1 in Head length: 4 cm/1.6 in Diameter: 1.8 cm/0.7 in Caution. Due to manual measurement, please allow 1-3 cm error. Due to differences between monitors, the image may not reflect the actual colour of the item.