This paper? provides a description of our Network Time Interface M-Module NTI supporting high-accuracy external clock synchronization by hardware. The NTI is built around our custom Universal Time Coordinated Synchronization Unit VLSI chip UTCSU-ASIC, which contains most of the hardware support required for interval-based clock synchronization: A state and rate adjustable clock device with a high resolution, automatically maintained accuracy intervals, interfaces to GPS receivers, and various timestamping features. Designed for maximum network controller and CPU independence, our NTI provides a turn-key solution for adding synchronized clocks to distributed real-time systems built upon hardware with M-Module interfaces.