a first locating member 70 is formed onto the preset location of the chamber 21 of the inner slide 20 and used to position the protruding end 52 of the angular inner rod 50 under preset maximum protruding state in the preferred embodiment the first locating member 70 is composed of a through hole 71 arranged on the side wall of the chamber 21 of the inner slide 20 and a bead 72 in the through hole 71 when the protruding end 52 of the angular inner rod 50 is under a preset maximum protruding state and when the inner slide 20 is retracted into the guide slot 13 of the outer cylinder 10 the interior of the bead 72 is solidly protruded from the chamber 21 of the inner slide 20 and abutted onto the limiting seat 51 of the angular inner rod 50 a tank 15 is laterally set on the guide slot 13 of the outer cylinder 10 when the inner slide 20 is pulled externally the bead 72 aligning with the tank 15 can be retracted for a release state such that the angular inner rod 50 can slide inwards a second locating member 80 is arranged between the guide slot 13 of the outer cylinder 10 and the angular inner rod 50 enabling the preset maximum.