The PF-5 soundproofing complex from SINTEC is composed of a flexible polymeric base made of EPDM rubber with mineral load additives. This produces a high density material and a non-woven felt of recycled cotton textile fibres, which are joined together using phenolic resin. This compound is widely used in the acoustic industry for the soundproofing of buildings. Its main applications are the direct reinforcement of materials that must be soundproofed, either on bricks, plates or PVC, and as stuffing in double brick walls or dry wall works.

However, the properties obtained with this bi-layer complex, which combines insulation and sound absorption (with a heavy layer and textile fibres, respectively), have turned the PF-5 into a widely used material for soundproofing solutions.