WHAT DOES FRT-15L3 MEAN?

I've tried out a number of diverse forced reset triggers, setting up with rare breeds authentic. When the ATF started off knocking on doorways though, I disassembled it, grinded it up and tossed it inside the trash as I didn't want any drama from a legally bought trigger. Anyhow, these triggers are awesome. The FRT-L3 is the greatest I have applied