The Back Spiral spin, also known as the Pendulum, Reverse Grab Spin or Backhand Grip spin, is a graceful addition to a pole dance routine. It is one of those pole dancing moves that helps the dance flow.
Tip: Don't grip the pole too tightly. It is going to feel weird for a moment when you are single-handedly holding your body while in centrifugal motion...you will have to get used to this feeling and as you progress you will trust that your arm will hold you until that back hand can grab the pole behind you and you continue to spin.
Don't give up if at first you cannot even go a full revolution around the pole. When I first learned this trick I had to go literally inches at a time until I could loosen my grip of that one hand.
Also, the father out you 'throw' your body from the pole, the better you will be able to spin.
Here is a video clip on how the spin is performed: