| Ant | High performance antenna for challenging EMI environments. Available with GPS option only. |
| DC | DC Operation: Requires the unit to be powered from a DC source exclusively, typically +12 to +35 VDC. |
| EXT | External Time Base: Available when a user prefers to reference the clock of an existing source of 1 MHz, 5 MHz or 10 MHz. Frequency is auto-detected. |
| LED | LED:Provides a front panel mounted "Time Code Lock" green LED. |
| OCXO | OCXO: Provides an Oven Controlled Crystal Oscillator. |
| Red | Red LED Displays |
| UL | "UL" Approved Power Supply: The unit is supplied with a UL/CSA approved wall mount power supply. |