“Shale packer” means a flexible rubber-like cone collar designed to fit between a well casing and a larger diameter hole and designed to prevent material placed above it from passing by it and into the well below.

Source. #7306, eff 6-13-00; ss by #9177, eff 6-13-08 (from We 101.32); renumbered by #12075 (formerly We 101.34)