What it does
Uses ceramic (eg non-metallic) test adaptor alignment sleeves to avoid metallic wear particles from contaminating active connectors
The connector adaptor body may still be metal for general equipment ruggedness.
Avoids later random operational failure of high power systems.
Connectors have been found to occasionally and randomly fail in transmission systems which operate over about 100 mW (+20 dBm).
Detailed studies have found metal particle contamination in every case.
The metal dust generally comes from wear particles caused when connectors are mated using a metal alignment sleeve in the through connector.
Test instruments are often the last item to be in contact with a connector.
Unfortunately, many instruments (particularly power meters) use a metal interface adapter. worst is anodized aluminium, which creates the most wear particles that will almost certainly result in connector contamination.