3.4mm hardware sofa bed spring: 1. material: steel, 2. usage: sofa 3. ... : 16mm to 25mm 4. diameter: 3.4mm protech (riqiang furniture hardware company) is a elastic webbing, mattress spring, pocket spring, sofa ... all over the world.The more details about 3.4mm hardware sofa bed spring is as follw:1. material: steel2. port ... .delivery time: 30 days12 . mini oder: 1 ton 3.4mm hardware sofa bed spring