Inside Dividers for Working at Height Here at Secure Tools, we offer a large selection of inside dividers for working at height. An inside divider, or inside calliper, features two adjustable legs that let you accurately measure hole diameters and distances between surfaces. We stock 4-inch, 6-inch, 8-inch and 12-inch inside dividers, each one made from top-grade steel that’s proven to handle decades of use without fuss - even in the most arduous of conditions. And, all of our inside dividers include a robust stainless steel attachment point so you can securely tether the tool to a harness or belt and stop construction site accidents and injuries when working from height.