The Grapner is the only clamshell grab for knuckle-boom lorry cranes worldwide able to dig even in hard soil without damage to the crane and to grab rocks up to 4 tons safely. Its patented kinematics and its high quality manufacture by a swiss company guarantee a lasting performance over many years.The Grapner allows, through the use of knuckle-boom lorry cranes instead of excavators, to speed up the execution of typical small to medium excavating jobs.