Dual-layered Vanadium Wire Springs. Wire springs are 2.36 inches (60 mm) in diameter and come sewn in to individual calico pockets. Innerspring support system is hand formed into a honeycomb-nested unit. For added support and comfort, the Shetland Superb features two layers of vanadium wire springs. Shetland Isle Wool Upholstery: The Shetland Superb is upholstered in hand-teased Shetland wool for a soft, absorbent sleeping surface. Mattress Border: Each Shetland Superb features a border that is 9.1 inches (23 cm) deep and reinforced with 3 rows of hand stitching on all sides. Each side of the Shetland Superb has air vents to promote air circulation and ideal temperature regulation. Borders are upholstered in protective wool as a finishing touch, featuring piped ticking for added softness. Exclusive Wool Fill: Each Shetland Superb bed features an exclusive wool fill that acts as a natural means of temperature regulation while also keeping the main sleeping surface dry. A Cover of Your Choice: Cover your Shetland Superb in any of the finest-quality worsted wool available through Vi-Spring. For more information, please contact a sales representative.