The lock channel is made of aluminum alloy, and the spring wire adopts a superior iron core and PE cover, which is sturdy and durable, matching each other perfectly. They can fix the plastic tightly to resist the storm and keep the greenhouse warm, having a wide application. 20 PCS Spring Wire & U-Channel. Different from the similar products of other sellers, our lock channel is made of aluminum alloy, which has the advantages of sturdiness, toughness, corrosion resistance, and rust resistance.The core of the spring wire is made of special iron, not easy to deform and break, and can firmly fix the plastic.