PROFLEX™ RCU-250 is an advanced composite sound control underlayment utilizing a combination of natural and engineered products to achieve superior IIC (Impact Insulation Class) and STC (Sound Transmission Class) sound reduction ratings. The product is also easy to install using a direct bond method, and is compatible with a variety of substrates and adhesives. PROFLEX' RCU-250 thickness is 250/1000 of an inch or 1/4″.