Bonnell spring: 13.5 gauge orthopaedic spring unit inners. Four sizes: Choice of single, small double, double and king. Medium firmness: Great for those who sleep on their side! Deep: Total depth approximately 18cm. Mattress: Get a Supreme 3000 deep quilted luxury mattress. Quilted: Made from a luxury damask fabric and helps to relieve pressure points across the body. Deep Quilted Luxury Mattress | Small | Living Social