The Starrett 91 Tap Wrench is strong and well proportioned. It is nicely finished and the gripping surface is properly tempered. It will firmly hold square or round shanks. It is plunger operated by knurled sleeve – the spring inside the sleeve causes plunger to back off when pressure is removed. 6" (150mm) Length, 1/16-1/4" (1.6-6.4mm) Tap Size removed.