Simmons Beautyrest 360 Westbury Plush 13.5 Mattress Only Twin XL 38x80 M272TXL. 1000 SERIES POCKETED COIL SPRINGS. Coil Technology: Individually Pocketed Coils Twin XL Coil Count 624 independently wrapping springs Edge Support: BeautyEdge Foam Encasement A high-density foam border that surrounds the perimeter of the spring system to prevent sagging when sitting on the edge