The most common type of flagpole installation is the in-ground foundation sleeve method which calls for 1’ of the flagpole to be encased in the ground sleeve for each 10’ of exposed flagpole height. The diameter of the sleeve should be at least 2” greater than the outside diameter of the flagpole with the area between the flagpole and the sleeve filled with dry sand. Sleeves with a 6” diameter are supplied with a base plate and grounding spike. Sleeves with a diameter of greater than 6” are supplied with abase plate, support plate, grounding spike and, for ease of vertical alignment, steel centering wedges welded to the inside of the base plate. If you require other sizes than listed or have special on-site conditions please give us a call 800-958-3009. We would be happy to help!