Highest elasticity and fatigue resistance.
The elastic packs are marked according to size and strength with symbols.
Every type can therefore be quickly identified.
Strength:
Strength ratings are based on the elastic being stretched 3 times the listed inner diameter.

Inner ⌀: 12.7 mm / 1/2 inch
Traction force: strong 4.0 N (400 g)

Inner ⌀: 8.0 mm / 5/16 inch
Traction force: strong 4.0 N (400 g) 

Inner ⌀: 8.0 mm / 5/16 inch
Traction force: light 2.2 N (225 g)

Inner ⌀: 9.5 mm / 3/8 inch
Traction force: light 2.2 N (225 g)