Fan cross reference

Can you please look into the following 2 fan part numbers. they are showing on your site as obsolete and I was not able to find a listed replacement options.

NMB-MAT
3110KL-04W-B19

and

NMB-MAT
3108NL-04W-B19

Greetings,
1688-2092-ND and P16997-ND might be alternatives to consider that are in stock at the time of writing. Note that the part numbers provided do not offer indication of the 3rd wire function, which is a thing you’d probably want to match.

In terms of finding alternatives, a product datasheet will often mention a suggested alternative product series:

Failing this, on part detail pages there are check boxes next to each product attribute; by selecting those which are non-negotiable (in this case, probably voltage, size, width, and bearing type) and clicking “view similar” one can quickly find all available product alternatives that share these key attributes.