The FFS Sonic Fence was developed specifically to control silvereyes (wax-eyes). With the exception of the ESC sound, the silvereye was immune to all known electronic bird control techniques and sound types. After extensive trials using many types of sounds and frequencies, the FFS sound was developed as a very successful silvereye repellent. All Bird Gard's combination units (ie: Crop Gard, Pro Amp, X-8, X-20 and MSF/BBC) which have several sounds in the one machine, include the FFS. The FFS also available as a unit on it's own.
The basic FFS Sonic Fence unit can be used to run a sonic fence (a series of speakers 30m apart) made up of as many as 8 speakers thus forming a wall of sound 210m long. It can also be used as a part of a multi-blaster, which is a 4 way (360 degree) speaker run by 2 sound generators. This enables the unit output 2 different sounds in a 360-degree circle. In either sonic fence or multi-blaster form, an 85amp fully charged battery will power the system, non-stop, for 2 to 3 weeks. As with all Bird Gard sound generators, the AVA is fully automatic. It has a light sensor that can be set with the flick of a switch to DAY, NIGHT, or 24-HOUR operation. There is no need to physically have to go and turn on in the morning and off at night, it's automatic.
The FFS, whilst principally a silvereye control unit, has been found to also be effective against blackbirds, especially when used in conjunction with the Electronic Scarecrow (ESC).