Flist ring nuts made of AISI 303 (X8CrNi 1809 1.4305 UNI EN 10088-1) stainless steel. Produced from a hexagonal bar they have a reduced thickness. That allow threaded connectors to be coupled to other equipment (boxes, cabinets, ducting) that have no threaded holes. The thread is ISO metric in compliance with CEI EN 60423.