A, High quality aluminum tube with aluminum treatment on the surface;                                                  B, Reinforced central vertical tube provides more supporting force;                                                                     C, Anti-skidding rubber feet-pad with metal gasket inside makes it more durable;                                           D, Rubber tube inside prevent it from metal friction;                                                                         E, Specially designed expansion tube offers more convenient adjustment;                                                         F, Sponge foaming armpit support and handle make it more comfortable to use;                                                G:9 Gears for height adjustment (gear distance: 2.5cm)