how can i make it so an if # statement has to be between two numbers to work?

i know the title is worded terribly, but i'm making a shift light for a car, and i set up a separate script to make it "flash" before it hits the optimal shifting point, but i want it to disable once the rpm value reaches a certain point

since i use "if rpm >= 8500 then script.Flash.Disabled = false"

then, i use "if rpm >= 9000 then script.Flash.Disabled = true"

but since the value is also over 8500, it enables the script, but also disables it at the same time is there a way to make it only turn on if its between 8500 and 9000? so then i can use the second if statement that i wrote down to disable it and have it stay disabled, so the light doesnt flash

any help is appreciated!