This Jerry Beagley Brain Trap Slides over the horses head and rests on the poll and brow.
It works closely as a tiedown in the sense that it prevents a horses' head from elevating too high, though a brain trap will allow the horse to still extend its nose.They are similar to a tiedown as the brain trap keeps a horses head from getting too elevated, but it will allow a horse to extend it's nose rather than keep it collected as a tiedown would.