Looking for rev-meter

[Christoph]

I would like to use a rev-meter to find out about....

Doing a search here leads me nowhere (my fault, using wrong wording???)
Doing a search at the vendors allways leads me to amp-meters....

There are no 6-Volt-rev-meter available, as all of them state: 12 Volt

Is it that its just about lighting in the meter or will it count wrong once
i attach a 12 Volt Rev-Meter to my 6 Volt car???

Thank you
Christoph