CRL Wood's 9" (229 mm) Diameter Vacuum Cups are available with a durable metal handle. Low Vacuum Audio Alarm supplements visible red-line indicator with an audible indicator, adding a measure of safety in circumstances that make it difficult to monitor the visual indicator. Plunger emits an audible warning to the user and others, in the case of a vacuum loss. Advanced design automatically turns Audio Alarm on or off as necessary, eliminating power switch, increasing battery life, and simplifying operation. Check valve allows re-pumping without loss of vacuum. Release valve lever permits quick and complete release. Supplied with protective Carrying Case.