JM Spider® is a Formaldehyde-free™, spray-in fiber glass insulation system that fills new and existing cavities without gaps or voids in the insulation coverage, for superior thermal and acoustical performance. Our unique design enables the fibers to more effectively fill tight spaces around pipes, wires and electrical boxes. Ideal for both retrofit and new construction, JM Spider® is naturally fire-resistant and does not promote the growth of mold and mildew. The insulation also installs faster and easier and does not settle over time.