The Bonnell spring is the classic Spring Unit, and has, through the years, proven its worth. It is made from around hourglass shaped springs which are tied together to form a mat. A round helical crosswise connects each single spring to a spring unit.

Different thickness (gauge) of wire in the springs makes a harder or softer mattress. The lower the gauge, the firmer the mattress is. So you can choose the softness of the mattress according to your need. The number of springs per mattress type is one of the key quality characteristics of a bonnell spring mattress.