Available to tap both UNC and UNF threads, 1528 Union Butterfield hand taps can be used for hand tapping a wide variety of materials including aluminum, steel, cast iron and stainless steel and have a bright finish which prevents workpiece material from sticking to the tool so you get cleaner, more accurate threads. Manufactured to conform to ANSI standards, they are made from premium High Speed Steel to provide great performance and extended tool life. 1528 UNC and UNF taps can be used for hand tapping a variety of materials including cast iron, steel, aluminum and stainless steel.