HSGI discontinued the Airborne model. Any other drop leg holsters out there for the FNX-45. I liked the Airborne , because there was a flapped model and it had the ability to hold two modular mag pouches.

http://www.kt-mech.com/kt_akela/ak_FNX45TAC.html

I found a flapped drop holster that fits the FNP/FNX-45. There is a double mag MOLLE pouch available that mounts horizontally along the belt line. The holster flap has velcro that holds it up when you don't need it. The mag pouches have velcro on the flaps also, so you retain the ability to have the holster flap held up with the mag pouches mounted. It also has a single spare mag pouch built into it, but I will probably carry a folding knife or a multi-tool in it.

Holster;

link

Mag pouches;

link

Here's the nutnfancy review on youtube (Blackhawk has made some slight improvements since this review in 2011);

link