Features: High quality: The expansion tube is made of high-quality plastic, which is environmentally friendly, has good tough-ness, is resistant to impact, is prone to fracture, and has a high expansion coefficient. Widely used: suitable for various types-of-surface such as concrete, brick, or gypsum. When applied to dry wall, it is recommended-to use lightweight projects. Working principle: When you tighten the screw, the expansion tube fully open and expands on opposite sides, increasing grip strength. The anti-rotation structure design of the expansion sleeve does not follow the screw during drilling-rotation. Easy to install: requires a drill bit to drill a pre-drilled-hole on the wall. The installation of each task is very quickly and simple . With these widely used plastic wall anchors and screws, you can almost handle all hanging projects like a professional. Specifications: Material: Plastic+Iron Quantity: 10 Packs Of 40 Pieces/5 Packs Of 20 Pieces Size: As Shown In The Picture Package Includes: 20/40pcs Expansion Tube with Screws note: Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. Due to the difference between different monitors, the picture may not reflect the actual color of the item.