Wire cutters cater for certain wires of specific diameters. They 'guide' the wire down their lengths of carbon steel to a 'cutting' section which is reinforced and designed to 'snip' the cable neatly in two
The operating arc of a perfect wire cutter kit should be from immediately below the tip path plane of the rotor blades to the lower edge of the undercarriage. In reality there are unprotected spots. of course, the kit is only designed to protect from wires ahead
I would imagine the main users are bush/cattle/ wire survey/camera etc operators. Thos who do NOE (nap of the earth) flying. UK emergency operators don't as a precedent, use them because our stats show us to be fairly quiet in the accident dept regarding wires...long may it last.
A wire cutting kit for an EC135: £30,000 sterling+ fitting.