Aero Precision upper receiver, 20" Shilen match barrel with matching bolt, Faxon bolt carrier group, Superlative adjustable gas block, Aero wide charge handle, and JP Enterprize 17" handguard. Aero Precision lower receiver, Timney trigger and Magpul butt stock. I have only sent 100-150 rounds through this rifle. It is very accurate and it is the smoothest running AR15 I have ever ran. The only reason I'm selling this rifle is because I have two Grendel's and I could use the money to help support my nasty ELR habit I acquired.