Trimble GEDO M8 Expansion Plug, 100-Pack Create secure survey reference mounting points in concrete structures with these Trimble GEDO M8 Expansion Plugs . Designed for track surveying and track marking applications, each plug features a durable plastic body with a brass threaded insert for attaching compatible M8 survey accessories. Key Features M8 expansion plug designed for mounting survey reference components in concrete structures. Plastic construction with brass threaded insert for secure attachment of compatible M8 accessories. Uses a screw-expansion mounting system and includes a plastic protective screw. Supplied as a pack of 100 expansion plugs for track survey and railway installation projects. Compatible With Trimble GEDO M8 track marking and survey accessories Compatible survey adapters and components using an M8 threaded connection