Get a great night's sleep without spending a fortune with the M963 Firm mattress from Sierra Sleep. The high-quality Bonnell coils give you proper balance and optimal support all night long. Covering the entire mattress, the High Density Support Foam provides further firm support along with the Poly-Foam layer. The polyester cover gives you a comfy top layer that works well with the firm support below. This mattress is ideal for stomach and back sleepers.