For the bonnell spring, Steel wire range, 2.1mm -2.4mm Helical wire range, 1.3mm or 1.4mm Border wire range, 4.0mm -5.0m Our company specialize in producing roll mattress, foam mattress. Compress spring mattress, leather bed, and sofa set. 1. Let body shape and mattess contact perfectly, It is good for protecting the skeletal. 2. Automatic balance and regulate pressure, promote the blood ...