A firestop system is a tested combination of the substrate (wall or floor), penetrating item or items, opening size, annular space and materials used to seal or protect the opening. To evaluate compliance with building code requirements, systems typically are tested by independent third-party test labs. Successfully passing the test means a firestop system is “listed” and the materials used in these systems generally are marked as “classified. “Several factors can affect the performance of a firestop system, all of which can be determined by examining the submitted system drawings. If a detail does not match the tested system requirements (e.g., pipe diameter and type, hole size, floor thickness, annular space), the installer must be able to find another tested system that matches the field application, or request and obtain a custom solution from the firestop material manufacturer. Finding appropriate systems can be somewhat daunting, as there are currently more than 7,000 tested systems for various applications.