Got a pair of these at the shooting show having seen them advertised as guaranteed to work or your money back (a bold statement i thought) anyway i have used them four times now and i am dead impressed, set up on Sunday but was way off a small flight line, but birds were spotting the rotary with the AirPro's on from miles away and just fell out off the sky, only finished on 31 but was very chuffed, used it last week on some beet tops for a 53 and again today for 13 before being called away after an hour. So far so good,