Large flat head screw is also a commonly used screw fastener. It means that the head of the screw is flat head, as shown in the above figure. We often call it flat head screw. Large head screw is also commonly represented by many letters, such as Ta, TM. TA represents large flat head self tapping screw, and T represents the head of the screw in the screw fastener, which refers to large flat head, also known as umbrella head, Because its head looks like an umbrella. The letter a represents the thread of the self tapping thread, Ta together is the large flat head self tapping screw, and TM represents the large flat head machine thread screw, because M represents the thread of the machine thread.