Grobet if new... old USA Nicholson or Simmonds. Can still be found NOS in small town hardware stores. Also I find right many old but like new files in antique stores of all places.
Do what you wish but,file "cards" are..... tough to say this and not sound prickly but,probably the worst thing you can do to a file. Well,besides scrubbing one backward or storing them on top of each other. Take a big brass cartridge case and smash the end flat.... makes cleaning a file a breeze.
Another tiny bit of controversy..... acknowledging there is a place that will sharpen your old files... name escapes me at the moment but it's about 8-10$ for a big mill bastard. And IIRC,you can sharpen one 2 or 3 times. That's the usual recommendation. The old timey,hence the controversy,way is...... during times of the year where you have a heavy morning dew,throw the file out in the yard for a cpl days. This was SOP in colonial times. I've done it and it works,just OK.