PROFLEX® SIM Crack KIT is an elastomeric membrane kit specially designed to be used under approved thinsets, mortars, adhesives, and is typically used to bridge existing cracks up to 3/8" in flooring surfaces. The 18" wide roll allows installers to cover up to 12" tiles on a diagonal pattern. SIM Crack KIT is ideal for making small repairs to substrates without the time and expense of applying PROFLEX® membrane to an entire substrate.