With a drilling tip, these metric screws cut their own pilot hole and threads as you fasten them into material. They’re often used to join two metal components together when you only have access to one side, such as when installing ductwork. Before screwing them in, countersink a hole so their flat head will lie flush in tight spaces and not snag other material. Made of steel, these screws are strong and wear resistant, and have a zinc plating to protect the steel from rust in wet environments. All meet ISO 15482 (formerly DIN 7504 P), an international standard for tapping screw dimensions.