Thick Bed Mortar System PROFLEX™ MSI is an installation system for installing tile and stone finish surfaces to a variety of substrates. The system uses PROFLEX' elastomeric Crack Isolation membranes, or our Hydra-Seal crack isolation and waterproofing along with a high strength ANSI 118.11 thinset style mortar (PART 1) and a Reinforced Portland cement based thick bed mortar mix (PART 2). These components work together to ensure a superior bond of tile and stone finish surfaces unmatched by other manufacturers.