"SMi™ Stepper motor gauges use a small electronic motor that only turns a tiny fraction of a rotation to drive the pointer. It is electronically controlled and is much more precise than the traditional mechanical instruments whose accuracy can be affected by many factors. Many professional race teams - NASCAR™, etc. – are switching to this style of gauge for the improved accuracy (see the in-car cameras). Approved for use by IMCA™. Built-in Warning Lights – Ultra Bright 2 Stage LED 2 set points are easily adjusted to your needs (critical oil pressure has 3 set points). For example set water temp for just above normal running temp (if you run 215° set it at 230°). Above that the LED comes on to let you know the motor is starting to get warm. Set the second one at the max temp your engine can tolerate (say 250°). At this point the LED flashes to attract your attention, possibly saving motor damage. Since oil pressure is so critical it has 3 set points. You can set the first just below normal running pressure (say normal is 60 psi – set it at 50 psi – no damage there). At this point the LED comes on. Set the second at 35 psi. The LED flashes – you need to know here, possible damage. Set the third at 20 psi. Engine damage is likely here. At this third set point the LED continues to flash PLUS the gauge backlight starts to flash. It’s hard to miss this – day or night. It allows you to get the engine shut down before it blows up, saving you $$."