Our Delta Core technique is a truly innovative approach to reducing the weight and bulk of the polyurethane (PU) foam core of our Self-Inflating mattresses Our patent pending coring process removes up to 40% of the initial volume of the PU foam, retaining enough for optimal support and comfort, while minimising the packed weight and size of the final mattress. Importantly, this coring technique has the additional benefit of keeping the top and bottom surface of the PU foam completely intact. This ensures consistent warmth along the full length of the mattress, avoiding the vertical holes or frame-like gaps that have traditionally allowed warmth to leach downwards. The full foam surface also provides significantly improved bonding of the foam to the shell fabrics of the mattress, thereby greatly reducing the chance of delamination. The shape and size of the Delta Cores are adjusted across the different thicknesses of our mattresses to ensure strength and durability, while still giving the user excellent support and self-inflating performance. The horizontal Delta Coring technique is used in our Comfort Light SI, Comfort Plus SI and Comfort Deluxe SI models.