The Starrett 91A tap wrench body holds 1/16" to 1/4" taps with 3/32" to 5/32" square shank diameters and is used to tap workpieces (requires taps, not included). A plunger-type spring-operated knurled sleeve applies and removes the tap when pressure is applied. Tempered gripping surfaces firmly hold square or round shanks. The tap wrench has a 6" overall body length.SpecificationsCapacity size (U.S.)1/16" to 1/4"Capacity size (metric)1.6 to 6.35 mmBody length (U.S.)6"Body length (metric)150 mmSquare shank (U.S.)3/32" to 5/32"Square shank (metric)2.4 to 4 mm The L.S. Starrett Company manufactures precision measuring tools, metrology and testing equipment, and saw blade products. The company, founded in 1880, is headquartered in Athol, MA.