since the use of the intrusion 163a 162a per fig1 is the preferred mode one such intrusion or groove 163a is shown also in fig2 for ease and convenience but the designator 29 is retained in that figure reference is made again to fig1 5 and 9 fig2 shows the crutch 10 of this invention in the closed or storage position while fig1 and 5 show the crutch or a portion thereof in its extended or use position in fig2 the first or stored position the coupling collar 31 will rest on the disc 33d of the height adjustment fastener 33 wherever that has been preset as previously discussed per fig9 in order to utilize the crutch the cap 41 of the crutch is manually removed by a downward yank from its set position within receiver 49 the crutch is held vertically to permit the moveable central leg 29 or 129 to move downwardly through the coupler 25 until the disc 33d mounted on the moveable central leg 29 comes to rest upon coupler 25 the user may hold the crutch upward at a convenient height but vertically with one hand and then couples the coupling collar 31 to coupler 25 by engaging the threads of the coupler 14 to those of the collar 26 to return the crutch to the storage position the procedure is merely reversed it is seen that any suitable materials such as plastic or metal or wood as employed in conventional crutches may be employed for the crutch of this invention except where specific materials have been called out it is seen that by selectively securing the height fastener to the moveable central leg the maximum travel of the moveable post downward through the collar is defined every time as.