An introducer sheath, comprising: a shaft including a tubular portion , an expandable portion coupled to the tubular portion and a longitudinal axis ; wherein the expandable portion includes a first pair of leaflets and a second pair of leaflets, and wherein both the first pair of leaflets and the second pair of leaflets extend along the longitudinal axis ; wherein the second pair of leaflets are spaced radially inward of an inner surface of the first pair of leaflets; and wherein the expandable portion is designed to shift between a first configuration and a second expanded configuration; wherein the first pair of leaflets includes a first leaflet and a second leaflet , wherein the first leaflet includes a first concave surface extending partially around the longitudinal axis , where the second leaflet includes a second concave surface extending partially around the longitudinal axis and wherein the first concave surface faces the second concave surface ; wherein the second pair of leaflets includes a third leaflet and a fourth leaflet , wherein the third leaflet includes a third concave surface extending partially around the longitudinal axis , where the fourth leaflet includes a fourth concave surface extending partially around the longitudinal axis and wherein the third concave surface faces the fourth concave surface ; characterized in that the third leaflet includes an outer surface and a first rib member disposed along the outer surface of the third leaflet , and wherein the fourth leaflet includes an outer surface and a second rib member disposed along the outer surface of the fourth leaflet . a shaft including a tubular portion , an expandable portion coupled to the tubular portion and a longitudinal axis ; wherein the expandable portion includes a first pair of leaflets and a second pair of leaflets, and wherein both the first pair of leaflets and the second pair of leaflets extend along the longitudinal axis ; wherein the second pair of leaflets are spaced radially inward of an inner surface of the first pair of leaflets; and wherein the expandable portion is designed to shift between a first configuration and a second expanded configuration; wherein the first pair of leaflets includes a first leaflet and a second leaflet , wherein the first leaflet includes a first concave surface extending partially around the longitudinal axis , where the second leaflet includes a second concave surface extending partially around the longitudinal axis and wherein the first concave surface faces the second concave surface ; wherein the second pair of leaflets includes a third leaflet and a fourth leaflet , wherein the third leaflet includes a third concave surface extending partially around the longitudinal axis , where the fourth leaflet includes a fourth concave surface extending partially around the longitudinal axis and wherein the third concave surface faces the fourth concave surface ; characterized in that the third leaflet includes an outer surface and a first rib member disposed along the outer surface of the third leaflet , and wherein the fourth leaflet includes an outer surface and a second rib member disposed along the outer surface of the fourth leaflet . <EOS>