Davtron Inc has determined that installation of all Davtron products are considered minor according to (FAR) 21.93(a). All of our units are similar in design, with their electrical, mounting size, and weight being similar. Even though we consider installation of Davtron products to be minor, it is up to the installing mechanic to determine if the installation is minor or major. For a minor, a maintenance log book entry is all that is required. The FAA has determined that the installation of replacement clocks in non-transport category airplanes is considered to be minor, therefore only a maintenance log book entry is required referencing letter 100S-GA-10-53 from the FAA.