A segmented nut has inner segments and an outer sleeve. Part of the sleeve interface portion and part of the segment interface portion engage when the sleeve rotates relative to the inner nut during release of the segmented nut with part of the segment interface portion at a greater distance from a central axis of the segmented nut than a minimum distance of the at least part of the sleeve interface portion from the central axis. One or more of the segments can include a retainer preventing the sleeve moving toward a free face of the segment(s). One or more of the segments can have a flange portion providing an increased working (compression) face relative to a plain segmented nut. An assembled segmented nut can include some radial freeplay for the segments to move radially whilst being retained within the sleeve prior to application of the segmented nut to a threaded bolt, stud or rod such that threading of the segmented nut onto the thread of the bolt, stud or rod removes the freeplay.