The Forney 20994 Industrial Pro 5/8-inch x 11 bottom tap high speed steel (HSS) bottom tap. Unified National Coarse (UNC). Includes 30-degree chamfer angle (approximately 2 pitches chamfered) and 1-1/2 tooth height. For tapping a blind hole where the threads need to go to the bottom of the hole. Forney Industries is one of America"s longest operating family-owned metal working product companies. Founded in 1932, Forney offers more than 5,000 products for the hardware, automotive, farm & ranch and do-it-yourself markets. If you"ve got metal working questions, we"ve got answers. Were committed to your success regardless of location size or needs. 5/8-inch(15.88mm)-by-11 bottom tap. Claims for warranty must be made within 90 days of the date of purchase. Proof of purchase required. This warranty does not cover any product that has been subject to misuse, neglect, negligence or accident, or that has been used in any way contrary to the purpose intended.