not knocking foxpro,i have 2.
but the mp3 systems with a good mp3 player,and a good pc recording system,i harvest far more with them.
put them in a small plastic,or metel box with some foam on the bottom and the top and it will play 2 nights on 1aaa,and 1 9volt,in 0 degree,on a sheet of ice,with no skips.
also as ive said many coyotes have been killed here the opposite of how you fellows do it,we look at the place we are certain the yote or fox will be coming,which doesnt happen all the time.
we set the call out put the sound we want on repeat,and use the sound that has whatever silence in front we need to get comfortably upwind 100 to 125 yards,this is daylight mind you.
the predator as i have had all fox,coyote,and bobcats will come in downwind of the caller,but when we were hunting downwind we seen very little and harvested very little,so we go upwind in the daytime.and make the shot apast the call,most of the time your average shot is 100 to 200 yards top,i try to limit to 150 but my friend dale shoots a 243 and a 6mm and he takes them many times at 250.
im like ben they all play the same sounds somewhat setup means more than anything.
but like any company they have to introduce new items to stay in business.
my friend bought a call called edge it is about the size of your hand the speaker is builtin and he can add 2gb of sounds,with a sd card.
the built in speaker is clear and loud enough but you can hook in a external,he got a big female last night on a pup distress,with it.