An item designed to be mounted around the extended hub portion of a gear, wheel, or the like, to retain it securely to a shaft by compressing the slotted hub body. the item may also be used to clamp around a shaft, or the like, to prevent end motion or to retain it in position. its compression quality is derived from a screw(s) or bolt(s) which may be a part of the item of supply. for items designed to secure directly to a shaft by use of setscrews, pins, or the like, see collar, shaft. excludes clamp, loop.