Johns Manville JM Spider Custom Insulation is a professionally installed spray-in fiber glass insulation system. It fills framing cavities completely, leaving no gaps or voids. This complete coverage results in superior thermal performance and sound control. The system uses fiber glass with 25 percent recycled content and is protected against mold growth with an EPA-registered mold and mildew inhibitor. JM Spider is part of Johns Manville’s complete line of Formaldehyde-free™ fiber glass building insulation. It improves indoor air quality, because it’s made without formaldehyde. Visit JM.com/formfree for more information on the benefits of JM Formaldehyde-free™ building insulation.