A device for storing and mixing bone cement components. The device includes a housing, a safety device, and a vacuum indicator. The housing defines a mixing chamber configured to store a first bone cement component therein. In a first safety position, the safety device prevents contact between the first bone cement component and a second bone cement component in the mixing chamber. In a second safety position, the safety device permits contact between the first and second bone cement components in the mixing chamber. The vacuum indicator restricts movement of the safety device from the first safety position to the second safety position when in a first vacuum indicator position. The vacuum indicator permits movement of the safety device from the first safety position to the second safety position when in a second vacuum indicator position.