Arc Fault Detection Device without rcd

one of our contractors has installed several Hagar ARM932U Arc Fault Detection Device.

After many enquires Hagar Technical confirm its only a MCB with AFDD.

The contractors insist its an rcbo as well , i put 550mA on an (RCD) Residual Current Device test  it did not trip.

this had made me wonder if others have come across such devices and where they are designed to be installed to?