Amazing and Simple
I was searching for pillows with an arch in them that was intended to keep my arm from falling asleep when I found this.  This is well worth the cheap price.  If it doesn't work for you, it can be returned; however it is only $10 bucks so it is worth trying.  This is a very simple product but it does what it says and has allowed me to sleep on my arm w/o losing circulation.  The only drawback is that it may not fit the arms of larger individuals or those with large biceps.
Rating: 5 stars