Flexsafe enables the implementation of single-use bioprocessing throughout all steps of drug manufacturing, from process development to production, upstream and downstream—using one polyethylene film. Flexsafe is based on a multilayer, polyethylene (PE) film, called S80, and has been developed in close collaboration with resin and film suppliers. A standardized cell growth assay has been used to optimize film formulation, determine the operating ranges for extrusion, welding, and gamma-irradiation processes, and to establish specifications and process controls. The optimization of the resin formulation, the complete control of raw materials, the extrusion process, and the bag assembly guarantee lot-to-lot consistent cell growth performance. With its 400 μm thick PE film, Flexsafe is strong and flexible. The bags enable safe and easy-to-use operation, even in demanding applications such as liquid shipping and large-scale stirred bioreactors.