The Johns Manville Spider Plus fiber glass blow-in insulation, now featuring interlocking fiber technology, is the next evolution of the JM Formaldehyde-free insulation family. Interlocking fiber technology allows the fibers to spring and lock into cavities with no adhesive or netting. This complete coverage results in superior thermal performance and sound control with a simple installation that's typically faster than other spray systems and unprecedented drying times, Spider Plus saves professional installers time and money on every project.