Flat headed wooden ladder (extra thick):
Grade 7 2.0 meters (extra thick)
Grade 8 2.4 meters (extra thick)
Grade 9 2.7 meters (extra thick)
10 levels, 3 meters (extra thick)
Grade 11 3.3 meters (extra thick)
Grade 12 3.6 meters (extra thick)
Grade 13, 3.9 meters (extra thick)