A coupling apparatus for coupling an inner tube and an outer tube, the inner tube being telescopically received within the outer tube, the coupling apparatus comprising: an adapter at least partly enclosing the inner tube and the outer tube, the adapter comprising a first end, a second end and at least one recessed portion, the first end receiving the inner tube and the second end receiving the outer tube, the adapter being coupled to the outer tube; a locking member received within the at least one recessed portion of the adapter, the locking member being configured to detachably engage with the inner tube to lock the inner tube and outer tube relative to each other; a sleeve at least partly enclosing the adapter, the sleeve comprising a first end, a second end and a retaining portion, the retaining portion being configured to detachably engage with the locking member to keep the locking member engaged with the inner tube; and a first constraining member disposed on the adapter, the first constraining members being engaged with the first end of the sleeve;a second constraining member is disposed on the adapter, the second constraining member being engaged with the second end of the sleeve; characterized in that the first and the second constraining members (138A, 138B) are spring biased such that the retaining portion of the sleeve detachably engages with the locking member, such that the sleeve is slidable towards the first as well as towards the second ends of the adapter against the spring biasing of the first and the second constraining members (138A, 138B) such that the retaining portion of the sleeve disengages from the locking member and the locking member disengages from the inner tube to allow the inner tube and the outer tube to telescopically slide relative to each other. an adapter at least partly enclosing the inner tube and the outer tube, the adapter comprising a first end, a second end and at least one recessed portion, the first end receiving the inner tube and the second end receiving the outer tube, the adapter being coupled to the outer tube; a locking member received within the at least one recessed portion of the adapter, the locking member being configured to detachably engage with the inner tube to lock the inner tube and outer tube relative to each other; a sleeve at least partly enclosing the adapter, the sleeve comprising a first end, a second end and a retaining portion, the retaining portion being configured to detachably engage with the locking member to keep the locking member engaged with the inner tube; and a first constraining member disposed on the adapter, the first constraining members being engaged with the first end of the sleeve;a second constraining member is disposed on the adapter, the second constraining member being engaged with the second end of the sleeve; characterized in that the first and the second constraining members (138A, 138B) are spring biased such that the retaining portion of the sleeve detachably engages with the locking member, such that the sleeve is slidable towards the first as well as towards the second ends of the adapter against the spring biasing of the first and the second constraining members (138A, 138B) such that the retaining portion of the sleeve disengages from the locking member and the locking member disengages from the inner tube to allow the inner tube and the outer tube to telescopically slide relative to each other.