It's a very nice gesture, and appreciated by many. Just like the donation to send G3 Surefires, useful pocket tools are reputedly hard to come by incountry.
Having served and deployed in a non-combat area, retired after 22 years USAR both Infantry and MP, simple lockbacks are the best to send, along with multitools. Large fixed blades are more problematic, can be restricted by unit commanders, and have little daily usefulness.
What the PX sells is what soldiers see, appreciate, and can accept, so folders from Spyderco, Benchmade, Buck, Schrade, etc seem to set the typical user. Extremely styled or wierdly ground exotics are largely a newb type blade and quickly shunned. Soldiers get around, see what the pro's carry (Ranger, Spec Ops, or E5 and above.) I would recommend simple straight blades with smooth handles, and avoid most knives with large letters on the blade, outlandish names, or bright, shiny blades with garishly colored handles.
Still and all, soldiers carry anything that works.
