These half-ring drill guides are for use with specific sizes of CDI-5400 and 6400 meters (3" or larger). They attach to the pipe by bolting into the rear half-ring that comes with the meter. They include a 3/16" drill bit, a 5/16" hex wrench, and a half-ring of the appropriate size to match your meter. When ordering, specify "XXX" to match your meter size (either 30C, 30S, 40C, 40S, 50S, or 60S). Guides for 4" pipe or smaller are $65, for 5" and 6" pipe are $95.