concrete double expansion anchor

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.

...

One of the primary advantages of double-threaded studies is their ability to provide a more robust and reliable basis for drawing conclusions. By examining the same phenomenon from different angles and perspectives, researchers can identify patterns and trends that might be overlooked in a single-threaded study. This increased level of scrutiny also helps to ensure that the findings are not simply the result of chance or random variation.

...