WHAT DOES FRT-15L3 MEAN?

I've tried various distinctive forced reset triggers, starting off with rare breeds original. When the ATF began knocking on doors although, I disassembled it, grinded it up and tossed it inside the trash as I did not want any drama from a legally bought trigger. Anyhow, these triggers are awesome. The FRT-L3 is the greatest I have applied thus far