birth alarms?

[echo]

I'm considering purchasing a foal alert type system, and would appreciate any info about the various options... Foal Alert, Birth Alarm, etc.
Thanks!

[Abejita]

two of the Standardbred farms I worked on used the one with the magnet you sew into the vulva..(magnet seperates from the transmitter upon a foot pushing through the vulva ,which in turn sets off the receiver which is set up to call a phone #. Possible false alarms due to a mare rubbing her butt so hard it seperates the alarm, and if something happens in foaling that the mare tears her vulva in a way that allows the whole transmitter to go off to the side it might not go off at all (low possibility..but possible)Taking %'s into account, I think it was a good device.

Another farm where we foaled Paso mares used the ones that attach to the halter.Idea is that if the mare lays flat out the alarm goes off..Dont know about you..but I think ALL of the mares I have ever watched ,in a double wide foaling stall lay flat out at least once a night...But the woman like the system..