Double-sided aluminum alloy joint telescopic ladder trestle ladder bamboo ladder folding stair multifunctional lifting household ladder 1.3+1.3 m, 1.6+1.6 m, 1.9+1.9 m, 2.2+2.2 m, 2.5+2.5 m, 2.8+2.8 m, 3.2+3.2 m, 3.6+3.6 m, 4+4 m