23 CEMENTING EQUIPMENT AND TOOLS-NAMELY, MOBILE CEMENTING UNITS, SKID CEMENTING UNITS, JET-TYPE MIXERS, PLUG CONTAINERS, CEMENTING PLUGS, PLUG VALVES, SAND SCREENS, BRIDGE PLUGS, STEEL LINERS, WELL PACKERS, SUB ASSEMBLIES, CIRCULATING VALVES, TUBING TESTERS, SETTING TOOLS, MULTIPLE STAGE CEMENTERS, CEMENTING COLLARS, WELL BORE WALL CLEANERS, SWIVELS, CLAMPS, PACKER SHOES, PACKER SETTING DEVICES, BAFFLES, CENTRALIZERS, TUBING SPACERS, CEMENT BASKETS, GUIDE SHOES, FLOAT SHOES, FLOAT VALVES, FLOAT COLLARS, BULK CEMENTING PNEUMATIC EQUIPMENT, PNEUMATIC HANDLING AND CONVEYING EQUIPMENT, BASKETS FOR PARAFFIN CONTROL MATERIALS, THERMAL UNITS, FRACTURING UNITS, FRACTURING HEADS, HYDRA-JET TOOLS, TUBING ANCHOR SWIVELS, HYDRA-JET CLEANOUT TOOLS, COLLAR LOCATORS, FRACTURING PACKERS, STRADDLE PACKERS, FRACTURING CROSS-OVER TOOLS, AUXILIARY VALVES, ANCHOR CATCHERS, TUBING HOLDDOWNS, DUMP BAILER UNITS, BRIDGING BASKETS, FORMATION TESTING TOOLS, HIGH PRESSURE CONTROL HEADS AND MANIFOLDS, REVERSING SUBS, PRESSURE EQUALIZERS, HYDRAULIC JARS, SAFETY JOINTS, FORMATION SAMPLING TOOLS, AND HYDRAULIC JETTING EQUIPMENT