Shadow Systems Glock 19 gen 2-4 MR920 complete lower. It does have an OEM Glock trigger bar and shoe to eliminate the Shadow Systems mushy trigger. Definitely makes a difference. Makes it like OEM. 

I ran a gen 3 and 4 on this from day one without any issues  it is a great frame  I'm just interested in a frame with a longer grip  or a gen 4 g19

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