Review on ⏱️ Runleader HM009 Round Hour Meter: Reliable Mechanical Timer for Boats, Cars, Fork Lifts, and More (6V to 80V Snap-In Quartz Timer) by James Jenkins

The counter inserts into a round hole for installation. To keep it there they didn't use a screw sleeve but a square clip that slides right onto the back of the gauge. Unfortunately, it's quite thick and won't interact with the gauge unless you install it from a material much thinner than my dash. I ended up breaking my clip when I tried to force it on and the workaround I found was to stick it to the surface of the dash with adhesive silicone gasket (I didn't have enough time to put one on before driving to get more meters).