Abstract: A stage tool used in a wellbore has a housing consisting of two sub-housings that couple together. A first sleeve is movably disposed in the housing bore and is held closed with a temporary connection relative to a side port of the housing. The first sleeve has a first seat of millable material. A second sleeve is also movably disposed in the housing bore and is held opened with a temporary connection relative to the side port. The second sleeve has a second seat of millable material. An opening plug is landed on the first seat so pressure can break the connection and shift the first sleeve open relative to the side port. After pumping cement out of the tool, a closing plug is pumped to the second seat so pressure can break the connection and shift the second sleeve closed relative to the side port. The first sleeve includes a bypass that allows for fluid to pass beyond the seated plug.