A magnetic resonance device chosen from the group of a magnetic resonance imaging device, a nuclear magnetic resonance spectroscope, an electron spin resonance spectroscope and a nuclear quadrupole resonance device, the magnetic resonance device comprising a cage with a fastening system for providing a stable, uniform and homogenous magnetic field in a sample cavity confined by said cage, said cage comprising: two main magnet assemblies being mirror images of each other; each of said main magnet assemblies comprising: a main magnet; a pole piece positioned on a face of said main magnet and a plurality of side magnets (20, 40), said side magnets substantially enclosing said pole pieces; the two main magnet assemblies being placed in a spaced-apart face-to-face relationship within said cage, thereby defining between said assemblies a magnetic envelope and enclosed volume corresponding to said sample cavity; said cage further comprising: side walls, wherein the number of side walls is equal to the number of side magnets (20, 40), said side walls substantially enclosing said side magnets (20, 40); and a plurality of fastening rods, wherein each of said fastening rods physically interconnects at least one pair of side walls, passing through at least one of said side magnets (20, 40) or at least one of said pole pieces. two main magnet assemblies being mirror images of each other; each of said main magnet assemblies comprising: a main magnet; a pole piece positioned on a face of said main magnet and a plurality of side magnets (20, 40), said side magnets substantially enclosing said pole pieces; the two main magnet assemblies being placed in a spaced-apart face-to-face relationship within said cage, thereby defining between said assemblies a magnetic envelope and enclosed volume corresponding to said sample cavity; said cage further comprising: side walls, wherein the number of side walls is equal to the number of side magnets (20, 40), said side walls substantially enclosing said side magnets (20, 40); and a plurality of fastening rods, wherein each of said fastening rods physically interconnects at least one pair of side walls, passing through at least one of said side magnets (20, 40) or at least one of said pole pieces. a main magnet; a pole piece positioned on a face of said main magnet and a plurality of side magnets (20, 40), said side magnets substantially enclosing said pole pieces; the two main magnet assemblies being placed in a spaced-apart face-to-face relationship within said cage, thereby defining between said assemblies a magnetic envelope and enclosed volume corresponding to said sample cavity; said cage further comprising: side walls, wherein the number of side walls is equal to the number of side magnets (20, 40), said side walls substantially enclosing said side magnets (20, 40); and a plurality of fastening rods, wherein each of said fastening rods physically interconnects at least one pair of side walls, passing through at least one of said side magnets (20, 40) or at least one of said pole pieces. side walls, wherein the number of side walls is equal to the number of side magnets (20, 40), said side walls substantially enclosing said side magnets (20, 40); and a plurality of fastening rods, wherein each of said fastening rods physically interconnects at least one pair of side walls, passing through at least one of said side magnets (20, 40) or at least one of said pole pieces.