Also called three way hobbles.
They are awesome for those horses that learn to run full speed with regular hobbles on.
Horses
should be trained with them before being left unattended.
A picket line also needs training. And should not leave unattended for long.
Hobbles are much safer in that regard.
Predators would be my only concern in leaving horses hobbled unattended. We leave ours out all night but the wolves aren’t around in the summer where we are.