Length adjustable connection structure

A length adjustable connection structure comprising:

• an adjustment assembly, an engagement assembly, and a receiving tube;
• wherein the receiving tube including an insertion accommodated in a first end thereof, a coupling portion formed on a second end of the receiving tube and having a diameter more than a diameter of the receiving tube, a groove defined in the coupling portion, a trench extending in the groove and away from the coupling portion, and an elongated slot defined in the trench;
• wherein the engagement assembly includes a fixing portion formed on a first end thereof, a toothed portion adjacent to the fixing portion, a fitting portion formed on a second end of the engagement assembly away from the fixing portion, a hexagonal hole extending from the fixing portion, and a circular hole extending from the hexagonal hole to the fitting portion, wherein a diameter of the fixing portion is more than a diameter of the toothed portion, and the diameter of the toothed portion is more than a diameter of the fitting portion;
• wherein the adjustment assembly includes a connector, a locating orifice defined in the connector, a hexagonal column extending away from the connector, a notch surrounding an outer end of the hexagonal column, and a C-retainer engaged in the notch;
• wherein the hexagonal column of the adjustment assembly is received in the hexagonal hole of the engagement assembly so that the engagement assembly is connected on the hexagonal column, the C-retainer is engaged in the notch of the hexagonal column, and the adjustment assembly and the engagement assembly are accommodated in the receiving tube, hence the toothed portion of the fixing portion is engaged in the groove of the coupling portion, and the fitting portion is fixed in the trench, thus connecting the adjustment assembly, the engagement assembly, and the receiving tube.