NMB produces a diverse array of fans for all your multifarious cooling needs. This used to include their 4710KL-05W-B40-E00 tubeaxial fan, but this product has since become obsolete. Its recommended replacement from NMB is 11925SA-24P-EAD-0, but this recommended replacement isn’t always available in stock. What options are left, once the recommendation is backordered?
Unfortunately, there’s no one single specific fan I can list here that will always be in stock, guaranteed. Fluctuating stock levels will hit every part eventually. What I can do is provide a parametric search link that provides close alternatives, such as this one: Close Alternatives to 4710KL-05W-B40-E00. This will take you to a list of fans that are both currently in stock whenever you click the link, as well as normally in stock in general, that closely match the key parametric values of the original fan. This should give you a great head start on locating an equivalent that will work for your needs.
Please review the datasheets to ensure the chosen alternative will work for your application.