WHAT DOES FRT-15L3 MEAN?

I have tried using various different forced reset triggers, starting off with rare breeds primary. When the ATF began knocking on doors even though, I disassembled it, grinded it up and tossed it from the trash as I failed to want any drama from a legally bought trigger. Anyhow, these triggers are awesome. The FRT-L3 is the greatest I have applied