Lead pig for use with screw cap vials.

Unlabelled: A lead pig specifically designed for use with solid screw cap vials is described.

Methods: The salient features of this design include a compressible polyethylene sleeve, which is housed in the lower section of the pig, and a partially recessed O-ring, which is housed in the upper section of the pig. These features permit both the vial and the cap to be secured independently without the risk of overtightening.