Concrete Penetrometers allow estimates of when concrete mixes are approaching their initial set. Concrete that has reached initial set can no longer be effectively consolidated, and is nearly ready for final finishing operations. ASTM tests define the initial set of concrete mortar as when 500psi (3.4mPa) of force is required to embed a penetration probe to a depth of 1in. Both penetrometer models are equipped with 1/20in² (32.3mm²) penetration plungers, which are simply pushed into fresh concrete at a constant rate to the mark scribed at 1in (25mm). Both can also be used in evaluations of mortars for unit masonry when equipped with the optional 2.7in (68.58mm) diameter HMA-295 Adaptor Foot.