6" spiral torsion spring is made of 60Si2Mn. 1/2" wide steel band measures 3 3/4" wide when fully coiled

External Mount Pivots feature 3, 4, or 5 spiral torsion springs and are suited for dump trucks using tarps from 16' to 26'. Optional mounting brackets are available. 
1. Quick and easy installation

2. Pre-assembled with 84" passenger side and driver side pivot arms

3. 3springs are recommended for up to 16 feet of tarp

4. 4springs are recommended for up to 20 feet of tarp

5. 5springs are recommended for up to 26 feet of tarp