In our Spring Facility, we manufacture "Bonnell Spring" for Mattress and Sofa Manufacturers from all world . The Height of "Bonnell Spring" can be manufactured from 100mm to 200 mm with 4-5-6 turns. Head diameter is from ø58 mm to ø90 mm with steel wire diameter from 1,90 mm to 2,45 mm. We apply heat treatment on "Bonnell Spring" in order to prevent sagging.