The 819M-PFR-1.0-2.5 Port Frame Reducer mounts onto the 2.5 inches port frame to change the port frame to 1 inch diameter. This allows accessories designed for smaller port sizes to be used with larger port frames. Coated with white reflective barium sulfate.  It replaces 819M-PFR-SF-2.5.  Tighten with two M3 size set screws using a 1.5 mm allen wrench, which are included with the part.