This crane puts actually two cranes together, auxiliary crane hoist the smaller tonnage while the other hoist the large tp prevent the slow hoisting and power consumption to the main crane when used pnly for hoisting the smaller tonnage, instead, the fast hoisting,power-saving and facilicated operation, twin crane save you one set of beams and the saddle seat, provides you more operating space with-out interference in between, amazing flexibility in the matching of tonnage and the models, for details,please contact us now.