The DeFelsko DOLLY20APK100 20 mm Dollies for PosiTest AT Adhesion Testers, Pack of 100 is ideal for use with PosiTest AT-A or PosiTest AT-M Adhesion Tester models for measuring coating bond strengths on metal substrates. Featuring spherical heads, PosiTest dollies automatically self-level on uneven surfaces. Precision-machined DeFelsko dollies are manufactured to exacting tolerances, to ensure maximum repeatability, and compatibility with all PosiTest models. DeFelsko dollies dollies maximize capability and measurement resolution across a wide range of bond strengths.