We got our theratogs yesterday!!  They are a bit complicated, you have to velcro the front of the "shirt" to the back, then velcro the bottoms into shorts and then velcro the shorts into the top....and THEN you  have to velcro the shoulders to the shorts!!  We are only doing it about an hour a day right now until he gets used to them, but I can tell a difference when he is in them, he sits up much straighter!