I use Boafeng UV-5R's. in short they're perfect for airsoft use, can even order a double pack like this: http://www.ebay.co.uk/itm/2PCS-BAOFENG-UV-5R-Black-Dual-Band-136-174-400-520MHz-Radio-UV-5R-Earpiece-UK-/172055945873?hash=item280f556291:g:2HYAAOSwNRdYB0BV
The only problem with them is...