A twin cylinder wing that forms a complete ring of air around the cylinders is sometimes referred to as a twin donut. They are not permanently attached to a back plate or harness, rather sandwiched between the back plate the cylinders themselves. Having a complete ring of air makes the wing very stable without a dramatic shift of air from left to right.
Much thought and design work has gone into the Apeks twin cylinder wings. Special attention has gone into the fabrics and hardware selected, the shape of the wing, the water drainage and the construction techniques. When you buy Apeks, rest assured that you are buying the best product available.