linkages or cables may be fitted to the constriction adjusting means for ease of operation spring loading to resist movements during shaking vibrating or gravity may hold the wedges in contact with the constricting means 3 covers to prevent foreign objects for example human appendages entering the contraction space may also be fitted in preferred forms of the present invention it can be seen that the present invention provides an adjustable length member 100 such an adjustable length member may find a variety of uses in providing for the adjustment in length and then locking of a member for example legs of a ladder etc the adjustment provided is preferably continuous between the maximum and minimum range in length of the member 100 preferred forms of the invention are robust in use in that they are relatively unaffected by contaminated by grease or other foreign bodies and or parts of the device are bound together thus limiting the chance of smaller parts being lost due to operator error in use it can be seen that at least the preferred form of the invention provides an apparatus in which the wedge or similar device can be used to change the dimension of the constriction to stop variation in the movement in at least a first direction between the two sliding members one of which is tapered in providing the apparatus in the manner shown the wedge tends to lock into the constrict when the sliding members are under a compressive load the compressive load tries to force the tapered member further into the constriction and can jam the wedge or similar adjuster in place this reduces any risk of.