Telescopic mechanism

A telescopic mechanism, comprising:

• a top tube;
• a bottom tube, slidably disposed around the top tube;
• a supporting tube, disposed in the top tube;
• at least one stroke tube, disposed in the top tube and spaced part from the supporting tube;
• at least one first positioning tube, disposed in the top tube and abutting against one end of the at least one stroke tube;
• at least one second positioning tube, disposed in the top tube and abutting against the other end of the at least one stroke tube;
• and
• a control assembly, connected to the bottom tube and having a positioning base, wherein the positioning base is movably disposed in the at least one stroke tube, the at least one first positioning tube, and the at least one second positioning tube,
• wherein when the positioning base is fastened with the at least one first positioning tube, the top tube is moved toward a first direction relative to the bottom tube to form a first length, when the positioning base is fastened with the at least one second positioning tube, the top tube is moved toward a second direction opposite to the first direction relative to the bottom tube to form a second length,
• a protrusion and a restoring elastic member, wherein the protrusion is fixed on the positioning base and faces the supporting tube, and the restoring elastic member is disposed in the at least one stroke tube and the supporting tube and pushes against the protrusion and a bottom surface the supporting tube respectively.