ADVANCED MATERIAL - These expansion bolt sets are made of high quality carbon steel, zinc plated to protect them from rust and corrosion, very strong and not easy to deform, durable and strong enough for you to hang your items. Easy to Install - The operation process is simple and labor-saving, the folding spring connection is suitable for larger wall thickness, you need to drill a suitable hole on the substrate and insert the hollow wall anchor into the hole, expand the anchor and complete the installation. Multi-purpose - Widely used in gypsum board, gypsum fiberboard, fiber cement board, hardboard, partition wall, hollow brick, prefabricated panel. It can be used to install light fixtures such as lamps, curtain rods, picture frames, hangers and electrical switches. Specifications - Size: M4 x 38. Quantity per pack: 25 pieces. Material: Zinc plated steel Product Description Our expansion bolt kits are just what you need for your renovation work. With this kit you can continue