The PSA AR-15 Stealth Lower Receiver.  Just the thing for that special build, this lower features no rollmark on the left hand side, just the caliber, model and serial.  Leave the area blank or engrave your own logo for the ultimate custom rifle.
These forged lowers are quality made by a mil-spec contractor using 7075-T6 aluminum and are marked "MULTI" to accommodate most builds.  Finish is Black Hardcoat Anodize per MIL-8625 Type 3 class 2.