The board I'm looking at is a modem board from a fax machine.

There are 2 identical components labeled VZ1 and VZ2 on the board, both components have F175 on the face and have 2 SMC leads.

One of them has a resistor across the back pins, and they look like they might be part of the power circuitry.

[![VZ1 and VZ3 visible in the top left and bottom right respectively](https://i.stack.imgur.com/bVJDE.jpg)](https://i.stack.imgur.com/bVJDE.jpg)