Abstract: A medical solution container having an outlet port with a neck that includes a tapered annular collar for slidably and sealingly engaging the hollow spike of an administration set. The inner and outer surfaces of the tapered collar slope inwardly, the collar defining an opening that is smaller (when the collar is unstretched) than the reduced portion of the bore of the neck communicating with that collar, thereby helping to assure effective contact between the collar and an inserted spike.