A geodetic assembly for land surveying, said geodetic assembly including: a first element including a first magnetic unit, said first element being attached to a geodetic device; and a support structure including a second element adapted to mate with said first element for supporting said geodetic device; wherein a magnetically sensitive device is arranged at said support structure; wherein the second element includes a second magnetic unit arranged to interact with said first magnetic unit for locking or unlocking said first element on said support structure; wherein each of said first magnetic unit and said second magnetic unit is divided in a plurality of regions (320a-d, 360a-d) arranged in a circular manner such that two adjacent regions have magnetic poles of opposite polarities; wherein said first magnetic unit is rotatable relative to said second magnetic unit such that the first element is brought in a locked position in which north and south poles of the second magnetic unit are in alignment, or at least approximatively in alignment, with south and north poles of the first magnetic unit, respectively, and in an unlocked position in which north and south poles of the second magnetic unit are in alignment, or at least approximatively in alignment, with north and south poles of the first magnetic unit, respectively; wherein said geodetic assembly further comprises at least one magnetic shield for shielding the magnetically sensitive device from said first magnetic unit and said second magnetic unit, said at least one magnetic shield comprising a first ferromagnetic cap arranged at a side of the first magnetic unit opposite to the side of the first magnetic unit that is arranged to interact with a side of the second magnetic unit for locking or unlocking said first element on said support structure, and a second ferromagnetic cap arranged at a side of the second magnetic unit opposite to the side of the second magnetic unit that is arranged to interact with a side of the first magnetic unit for locking or unlocking said first element on said support structure; and wherein said first element includes a recess in which said first magnetic unit and said first ferromagnetic cap are arranged such that said first magnetic unit is arranged to interact with said second magnetic unit by inserting said second magnetic unit and said second ferromagnetic cap in said recess to lock or unlock said first element on said support structure. a first element including a first magnetic unit, said first element being attached to a geodetic device; and a support structure including a second element adapted to mate with said first element for supporting said geodetic device; wherein a magnetically sensitive device is arranged at said support structure; wherein the second element includes a second magnetic unit arranged to interact with said first magnetic unit for locking or unlocking said first element on said support structure; wherein each of said first magnetic unit and said second magnetic unit is divided in a plurality of regions (320a-d, 360a-d) arranged in a circular manner such that two adjacent regions have magnetic poles of opposite polarities; wherein said first magnetic unit is rotatable relative to said second magnetic unit such that the first element is brought in a locked position in which north and south poles of the second magnetic unit are in alignment, or at least approximatively in alignment, with south and north poles of the first magnetic unit, respectively, and in an unlocked position in which north and south poles of the second magnetic unit are in alignment, or at least approximatively in alignment, with north and south poles of the first magnetic unit, respectively; wherein said geodetic assembly further comprises at least one magnetic shield for shielding the magnetically sensitive device from said first magnetic unit and said second magnetic unit, said at least one magnetic shield comprising a first ferromagnetic cap arranged at a side of the first magnetic unit opposite to the side of the first magnetic unit that is arranged to interact with a side of the second magnetic unit for locking or unlocking said first element on said support structure, and a second ferromagnetic cap arranged at a side of the second magnetic unit opposite to the side of the second magnetic unit that is arranged to interact with a side of the first magnetic unit for locking or unlocking said first element on said support structure; and wherein said first element includes a recess in which said first magnetic unit and said first ferromagnetic cap are arranged such that said first magnetic unit is arranged to interact with said second magnetic unit by inserting said second magnetic unit and said second ferromagnetic cap in said recess to lock or unlock said first element on said support structure.