Moulded plastic plates, similar to the Canford 40-991 D-series blanking plate, designed to accept a BNC connector. 13mm hole with anti-rotation flat. They are designed for metalwork prepared for, and to match with, reverse mounted 24mm connectors.
40-298 has M3 metal threaded inserts, permitting a faster assembly as nuts are not required.
Manufactured by Canford.