Use the Tempest Advanced 150 Skull Cap to create a peak to the front of your Tempest Advanced 150, to give greater protection from the rain without compromising the view of the lake. Not only does the Skull Cap give additional protection from the weather due to the peak created to the front of the shelter, it also adds a second skin to the top of the shelter to combat condensation and retain heat. Unlike a full overwrap, it can be left in place when the bivvy is packed down.