Heavy duty construction Professional use / Residential use / DIY The ladder extends in 1' foot increments and folds to 36.5" in height when not in use Easy to close & store away EN131 certification = 330 lbs max load Aerospace engineered 6061 aluminum alloy construction No pinch closure system Non slip bottom end Carrying handle Heavy duty closure strap Space Between Two Rungs: 14" inch (35.5cm) Thickness of Aluminum: 1.3mm