Abstract: A container includes a top-open container body having a tapered top-flange around the top opening thereof, and a top cover having a tapered bottom flange fitted around the top flange of the container body, wherein the top cover has a stepped air hole and a push-button plug assembly mounted within the stepped air hole and pressed to control the passage; the top cover has a recessed retaining portion moved to engage with a raised retaining portion on the container body for letting air pass through air guide grooves on the top cover and container body into the inside space of the container body.