crystal frequency

I got a couple of crystals in the standard hc-49 package and the only thing written on them is :
R040JAB4u
Anyone got an idea what's it's frequency?

You're probably not going to find anything Google is a complete blank for that number and that's not common. So it's probably an inhouse part number which you'll never be able to reference. To find out it's value you'd have to plug it into an oscillator circuit and determine it's frequency through trial and error, with a scope possible to determine the relative amplitude values to determine what harmonic it's oscillating in.

I see, thanks a lot