"Zero Percent Blank" (commonly referred to as "80%" in the industry.) non-firearm design, for repairing an existing receiver , display, or any other lawful purpose. If you own a 16s or CYPHER, this is a backup that you should have at least one of in your parts bin.An FFL is not required for shipment-Machined from 6000 series extrusion-Patent Pending Design-Based off our ATF approved, non-firearm design-16S Dimensions-Unfinished, tumbled, deburred, and in the white, to allow for custom finishingFeatures that do not make it a firearm-1-Does not have the bolt carrier guide rail channel finished2-Barrel Clearance Cavity unfinished3- Barrel Index Notches unfinished4- Barrel Mounting Screw holes undrilledPlease make sure this item is legal in your locality.