Annex 1 of the EU Guidelines for Good Manufacturing Practice (GMP) outlines specific requirements for barrier systems that prevent contamination in the production of medical products. It forms the basis for the Contamination Control Strategy (CCS) and Quality Risk Management (QRM), which are essential for enhancing product quality and ensuring patient safety. Barrier systems are particularly critical during the product filling process, where contamination risks are highest. One such system is the isolator, which provides a controlled, sterile environment for the process. This presentation will focus on isolators, detailing their design, function, and how they help meet the stringent regulatory requirements of Annex 1 to ensure compliance and safeguard product sterility.