This is the size that is and has been the most standard in the marine industry for instruments (excluding Tachs and Speedometers) such as Teleflex, Medallion, Livorsi, Gaffrig I & II, Faria, VDO, Autometer, Stewart Warner & Beede where the size of the instrument housing and size of the dash mounting hole are approximately 2 1/16". Outside diameter of the bezel is 2 3/4".