A new lower limbs exoskeleton model for builder and rescue workers, firefighters, and personnel of other emergency services is proposed in the paper. The proposed exoskeleton model is more comfortable than the existing ones because it uses links of alterable length and artificial resilience resulting from the magneto-rheological fluid utilization in the link design. The utilization of this fluid makes it possible to control link stiffness by applying external magnetic field. The exoskeleton has four links of controlled length and the same design. Each link includes the absolutely rigid bottom part with a cylinder attached to it and filled with magneto-rheological fluid. A coil of wire is wound on the cylinder surface. The coil is energized by the electric current when required. The top part of the link includes a piston inside the cylinder with a stem passing outside it. The piston moves inside the cylinder filled with magneto-rheological fluid. The piston features microscopic channels through which the magneto-rheological fluid can flow relatively easy in the absence of magnetic field. If magnetic field is applied, the particles of magneto-rheological fluid are arranged in a way to prevent free flow of the fluid through the piston. Thereby the link stiffness, and consequently the link length control are implemented. The paper lists results of numerically found lengthwise forces applied to the piston in the cylinder filled with magneto-rheological fluid. The proposed exoskeleton model can be widely used by builder and rescue workers because of its comfort, high-speed performance, noiselessness, and great developed force.