comprise a heat sealable flange 24 that is sealed about the edge 26 of the opening in the inflatable 22 representative heat sealable flanges are disclosed in u s pat nos 2 219 190 4 015 622 4 927 397 and 6 009 895 the disclosures of each of which are hereby incorporated by reference herein as shown in fig2 and 3 check valve 10 of the invention comprises a poppet 30 having an annular groove 32 in which is positioned an annular o ring 34 that seats on an annular seat 36 formed at the end of the lumen 38 of the upper body 12 u the poppet 30 includes a generally concave portion 46 having an upstanding protrusion 42 extending from the inside center thereof protrusion 42 comprises four interior webs 42 w positioned at 90 degree intervals and forming a semi spherical outer configuration poppet 30 further comprises three exterior webs 44 positioned at 120 degree intervals and being slightly tapered inwardly from the lumen 38 of the body 12 cap 14 comprises a plurality of tabs 14 t that snap into corresponding slots formed in the outer periphery of the cap 12 to securely retain the cap 14.