Done a number of these the first ones were ordered with UK Nato plugs came with Nexus US Nato.
HS inc were not helpful, I was asked what is a UK Nato !.
We said we would buy fit correct plugs as ordered & only charge for components or they could ship the correct item to us, the reply was NO, so We swallowed the cost
but left a bad taste regarding any problem in future.
Saying that we have not had a problem, just fitted a set in Hughes 500s helmet, he will give you a report, in mine it works ok but we fly with doors on he does load lifting.
Don't know if they do different size jell seals as one comment was they are small for my ears.
They either work of battery box or can be ship powered with small PSU. The power lead can be incorporated in headset wire it has a screw fitting