Introducing the Spring Inside Caliper by POWERTEC This handy tool allows the user to quickly and easily measure the inside dimensions of objects in a vast array of projects. Great for use in projects involving the measuring of holes and inside widths, for example, when measuring the inside of pipes/tubes, mortises, bowls, vases, or boring your work piece on a lathe. The possibilities are unlimited. Easy Use, Dependable Precision To use, lightly squeeze the caliper to release tension and slide the specially-machined nut to the rough location of your measurement. Then fine-tune and tighten to lock in the setting. Proceed to measure the gap with desired scale for accurate determination. It's that easy. Easily transfer the specifications to make sure the diameter of your project stays inspec, to replicate project dimensions, or when creating layouts for future work. Rugged Durability With a rugged construction of carbon steel with solid brass fittings and hardened steel fulcrum, tip and spring, this high-quality tool will last through many years of successful production. Clear coating ensures wear resistance and provides an attractive finish. · 8-Inch, inside caliper for the precise measuring of inside diameters · Specially-engineered speed nut insures accurate, quick and fine-tuned adjustments for ultra-precise measurement; spring tension aids in steady controlled action · Constructed of premium carbon steel with solid brass fittings and with hardened steel points, fulcrum and spring · Great for woodworkers (essential in woodturning projects), metal workers, machinists, plumbers, craftsman, builders, makers and more