I assumed since you had commented on this thread;
https://forum.45homelab.com/t/my-hl15-1-0-fan-filter-retrofit/3511
that you were aware of the basic mechanics of the filter kit install. As you can see from the top down photos, there is an approximately additional 3mm gap left between the fans and the drive cage. You may be able to fit 28mm specialty fans in there, but I’m not sure 45HL is going to commit to a build tolerance for that within mms. It should be clear that 38mm is a fantasy.
The normal gap between the front and the drive cage is only about 40 mm. If you want to try to use 38mm fans, and install filtering, your better bet is to just replace the fans as they are normally mounted to the faceplate and install external magnetic filters over the intake holes. I don’t think I’ve seen any posts of others installing 120x38 fans..