CMC is considered the original drop-in trigger group. CMC has been manufacturing triggers for the AR-15 and AR-10 platforms since 2003. Using a proprietary machining process, CMC’s critical sear engagement surfaces have a superior surface finish and dimensional control.
All CMC drop-in triggers are designed to be easy to install whether you’re upgrading an existing AR or building a new one. They’re available in several styles and finishes ranging from basic single-stage triggers to two-stage triggers that can be flat, curved, gold, etc.
And best of all, all CMC drop-in triggers are made in Texas.https://www.guns.com/news/best-ar-trigger-manufacturers