The protective bellows for laser cutting machines have two distinct applications: bellows for the mechanical parts and bellows for the optical path. The bellows for the mechanical parts are made of fabric with high fatigue resistance, while the bellows for the optical beam are more complex because they must ensure the tightness of the pressurisation gas and confine any divergence of the laser beam with internal metal inserts. The fabric must also be self-extinguishing and must not release dust on the inside. PEI has long been a leader in the construction of both these types of bellows protectors.