The pre-drilling system was controlled by computer, which can guarantee the all the sizes of holes can be very exact. Our steel purlins are roll-formed by Hi-Tensile Galvanised steel strips, and it consists of Z purlin and C purlin. The pre-drilling system was controlled by computer, which can guarantee the all the sizes of holes can be very exact. Cross sectional shapes of C purlin are reasonable and economical , reasonable design greatly decrease the roof weight of buildings and the cost of steel. Also, the standard range to suit your individual requirements. Advantage: 1. Light weight and high strength 2. Anti-corrosion 3. Good durability 4. Water and fire proof 5. Cost-effective 6. Repeated use