Outside Dividers for Working at Height Here at Secure Tools, we offer a small selection of outside dividers for working at height. An outside divider, or outside calliper, features two adjustable legs that let you accurately measure both the exterior diameter and thickness of an object. We stock 4-inch, 8-inch and 12-inch outside dividers, each one made from high-quality steel that’s proven to endure decades of use - even in the toughest of conditions. And, all of our outside dividers include a hard-wearing stainless steel attachment point so you can safely tether the tool to a harness or belt and prevent construction site accidents and injuries when working from height.