Pocket Sprung. Soft To Medium Tension. 6 Air Vents. Hand Tufted.This Symphony 1000 mattress by Airsprung has 1000 pocket springs in a kingsize mattress and has a soft to medium tension. The mattress is pocket sprung this system is where each spring is sewn into an individual fabric pocket allowing each spring to move independently and responds to the bodys every movement and contour. Along the side of the Symphony from Airsprung which is a hand tufted mattress there are 6 air vents that are there to help ventilation. Suitable for a wide range of divan bases, or bedsteads that are available on our website.