2-Ear Pinch Clamp, Zinc Plated Steel, 0.787 - 0.905 Inch Clamping Range, 0.354 Inch Width

You want the hose OD to land inside the clamp’s 0.787 to 0.905 inch clamping range. A hose that is about 7/8 inch, or 0.875, sits right in the middle of that range, so it’s the right size window for it.

Close the first ear all the way down before you touch the second one. Once that first ear is fully closed, then close the second ear just enough so the first ear opens back up a little, roughly a 1/16 inch gap. That slight opening builds tension into the clamp, kind of like a spring, so it holds firm against pressure, vibration, and any hose shrinkage that happens over time from heat or aging.

These Oetiker 2-ear clamps are indeed used for securing lines carrying fluids, including fuel, as well as air, gas, and steam in industrial settings.