This invention relates to a valve apparatus for use in metal casting and methods of its use. The power apparatus has a plug, which can be inserted into a cigarette-lighter socket in the car to become a power source for the driver alarm. The protective covers are supplied in stacks, mounted on a rod, and may be torn off one by one. Based on a comparison of the measured signals, a meter can determine whether the sample is a control solution or an actual patientuser sample. Further, the dental syringe may comprise a tip retention insert which may use either a pair of plates or a plurality of ball bearings to retain the dental syringe tips.