1.Halves bean appearance,smooth surface,convenientoperation.Concave type design ordinary matrix band andsubgingival matrix bands make it easy to recover to thenormal adjacency relations. 2.Designed with holes and protrusions for easy clamping,placement and removal. lt conforms to the extended shapeof the gums at the neck of the tooth and forms a concavesurface on the adjacent enamel ridge, giving it a greatercurvature and wrapping the tooth surface more stably.