Caliber .45 cartridge Signal RED info help!

I have this box with one cartridge and I like to know what the use of this cartridge was?
Is it a tracer or more like a flair cartridge?
headstamp FA 35

Gyrojet–It is a tracer, but it’s designated use was for signaling. But unlike most flairs it does not burst in a star effect. It also comes in green, with a green tip. Be aware, if yours has not already done so, expect it to crack the bullet and case due to swelling of the tracer compound. 90% of them are cracked by now. Both of my red and green ones which were in perfect shape when I got them in the 1970’s are now cracked.