Abstract: A blow molded plastic cap is provided, having multi-start external threads, the bottom rim of its body being engagable with multiple internal threads of a blow molded plastic container to effect a seal therewith. The interlocking of the threads compresses together the cap and the container forming a seal therewith provided by the side wall and the top wall of the cap in combination with the side wall and the top flange of the container.

Abstract: The present invention provides an injection mold apparatus for plastic piece molding. The apparatus includes male and female body parts and a gas blow-off ejection system for ejecting pieces formed on the male body part. The blow-off system includes side and top opening vents in the male body part for initial release and slight lifting of the piece and a further bottom positioned final blow-off vent, which is covered by slideable means during introduction of the plastic to the mold to prevent the plastic from flowing into the final blow-off vent and which is only exposed when required for completing blowing of the piece from the male body part. The slideable means has a slide tolerance to substantially eliminate flowing of the mold material therearound while being readily slideable when required for exposure of the blow-off vent to the male body part.