Shunda has been manufacturering heat-treatment steel and related products for 18 years since 2002 and has several Patents for Invention which are the guiders of our superior quality steel strips.

About the spring box for roller shutter door, there are 4 types for choice: metal ball type, metal bearing type, nylon ball type, nylon bearing type.

Metal ball spring box

Metal bearing spring box

Nylon ball spring box

 Nylon bearing spring box