This style of headset is fairly popular amongst Airsofters who make use of team communication. With a single padded earpiece (left side)it leaves the other side clear for environmental observation and even the covered side is well vented enough to hear through it when not in use.
Adjustable, elasticized straps cover over the head; one behind the head, one across the forehead and one band over the head. The result is a secure but flat-packed set of straps that can be worn under a helmet or over a baseball cap. There are particular military style helmets with ear slots to accommodate such a headset and the straps can easily be worn under or over a baseball cap if tuned right. Of course, you can just throw it over your head as is for that spec ops / mercenary look.
The microphone sits on a highly repositionable boom rod which means you can adjust it to your face very quickly or tuck it away when out of use; also handing for packing it up as you can bend it around on itself to tuck it into a sort of parcel.
Note that this is literally just the headset; this works in conjunction with a Z Tactical PTT button module (not included) and a radio (not included) to form a functioning comms setup. Of course that does not account for the fact that your team mates need that too otherwise you will just be talking to yourself.
There are a variety of different models and colors around the website and with PTT modules you have to make sure you pick the right plug type for the radio you intend to use. That said, do make sure you whip around the site and are sure you have found the right equipment to suit your tastes and needs.