Merck, Z273554-1EA, Molykote high-vacuum silicone grease

General description
Seals and prevents freezing of stopcocks and ground-glass joints in high-vacuum systems at pressures less than 10-6 mm Hg. Heat stable (−40 to 204 °C), low vapor pressure, and chemically resistant. Colorless. 5.3 oz. tube.
Application
High-vacuum silicone grease can be used:

to coat the cloning rings used for hypoxanthine phosphoribosyltransferase (HPRT)-deficient cells selection and isolation
to coat the cloning rings used for selecting the transformed cells during BALB/c cell transformation assay
to seal a cover glass over a petri dish containing culture for bioluminescence detection