plastic expansion bolt

Self-drilling screws, as the name implies, eliminate the need for a separate drilling step, as they have a cutting tip designed to pierce through material without requiring a pilot hole. This not only saves time but also reduces the risk of material damage that can occur with traditional drilling methods. The 1 1 4 self-drilling screws refer to a specific size, which typically signifies a 1/4-inch diameter and a 4-thread pitch. The numbers '1' and '20' often represent the diameter in imperial measurements, while '4' indicates the number of threads per inch.

...

The term 16mm refers to the length of the screw, which is about 0.63 inches. This size is particularly useful in various applications, offering enough length to secure materials without penetrating too deeply, thus maintaining structural integrity. While they come in various diameters and thread configurations, 16mm self-drilling screws can generally accommodate a range of thicknesses in materials, making them a popular choice in construction and industrial applications.


...