5 working load = 5 normal classes
For a quick visual control, each class have a special base shape.

A Class	B Class	C Class	D Class	E Class

With each props in each class you have: A permanent safety device between main and inner tube A stop adjusting nut system A 100mm clearance for hand safety A reinforced base A fingers protection against pinching A hot deep galvanisation protection A captivated retaining pin To control your prop Exemple : B35T (B = class B, 35 = 3m50 hight maxi, T = covered threads) E40N (E = class E, 40 = 4m00 hight maxi, N = external threads)

N type (left) external thread T type (right) covered threads