Protechmaterial is a leading manufacturer in South China specializing in furniture elastic material and relatived hardwares, and with a long export history since establishemet 1983. The company's production base located Shunde. The biconical spring more details is below: Width:5cm-7.2cm Heigt:8cm-22cm Diameter:1.6mm-4mm Round: 4-6 Sell: by kilogram Port: shunde Payment:30 deposit Delivery time: 25 day Mini oder; just for your oder Available in various designs and specifications for your selection. They are used for the bed or sofa. The more detail information is as follow: