Stopper-shield assembly

A closure assembly for sealing an open end of a body fluid collection tube comprising:

• a stopper comprising an annular stopper body with an integral upper flange portion;
• a lower integral annular sealing portion on said body;
• an annular notch in said body at the interface of said upper flange portion and said lower sealing portion;
• wherein the outer annular surface of said lower portion being the sealing surface with a container and tapered inwardly continuously toward the axis of said body, said taper being from said annular notch to the bottom surface of said lower annular sealing portion;
• said bottom surface of said annular sealing portion being convex;
• and
• a flexible cap body for mounting on said stopper comprising a top surface, a bottom stop ledge, an annular skirt extending from said top surface to said bottom stop ledge;
• said annular skirt comprising an outer wall surface and an inner wall surface;
• a central opening in said top surface;
• an integral annular abutment on said inner wall surface with a tapered surface;
• wherein said integral annular abutment having a width of 0.011 to 0.021 inches and said annular skirt having a width of 0.008 to 0.018 inches with respect to said center-line axis.