Bonnell spring: 13.5 open coil bonnell spring for a longer mattress life. Hypoallergenic: Dust mite resistant and hypo-allergenic for allergy prone users. Six sizes: Available in six sizes from small single - super king. Spring mattress: Get a quilted cool memory spring mattress. Bedroom essentials: Perfect addition to any bed set! Micro-quilted: Durable micro quilted sleep surface for maximum support when asleep.