Lighten up so you'll be the one singing the last mile into camp. The Spark doesn't compromise comfort or warmth to shave ounces. We use partial Flex construction to keep the luxury meter pegged without adding noticeable weight. You'll sleep more comfortably, and more warmly, than ever before with Flex. Just to prove we're still attached to the details, we include all the bells and whistles, like Foot Box Venting, to make our Ultralight Spark as comfortable as bags weighing twice as much.