Sea to Summit Ultra Light S.I. Thick light and easy-to-use. From backpackers trying to shed grams to car campers who want glamping luxury our range of self-inflating mats provide consistent warmth along the full length of the mat in a compact comfortable easy-to-use package. Delta Core-V In our lighter models Delta Core-V™ vertical coring technology is applied to remove 20% of the weight and bulk of the mat's polyurethane (PU) foam. We use sophisticated pressure-mapping data to define body contact areas which becomes the blueprint for our distinctive graduated core pattern. In body contact areas where extra warmth and support is needed - shoulders hips and feet - the vertical core holes are smaller. In the less critical areas more foam has been removed to minimise the weight and packed size. Delta Core-V™ technology is used in our Ultra Light SI and Camp Mat SI models. Pillow Lock Sys...