Dual-layered Vanadium Wire Springs: Wire springs are 1.97 inches (50 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 Signatory features two layers of vanadium wire springs. Mattress Border: Each Shetland Superb features a border that is 9.1 inches (23 cm) deep and reinforced with 4 rows of hand stitching on all sides. Each side of the Signatory has air vents to promote air circulation and ideal temperature regulation. Borders are upholstered with all-natural coir and wool, featuring piped ticking for added softness. Shetland Isle Wool Upholstery: The Signatory is upholstered with authentic Shetland Isle fleece wool for soft sleeping surface that naturally regulates mattress temperature and humidity. Plush Cashmere Comfort: The Signatory is the first of the Vi-Spring luxury bedding collection to feature a full layer of premium cashmere. A material once reserved exclusively for royalty, the cashmere comfort layer of the Signatory bed adds a touch of exquisite softness that is not found in any other luxury bed. Custom, Exotic Inner-mattress Fills: Choose from pure cashmere, hand-teased long stranded horsehair, Shetland Isle fleece wool, fine silk, and mohair.