Those are AR-15 lowers. We are talking AR-10 /.308 lowers.Best deal I've found on raw AR lowers lately is from Always Armed
AR15 80% LOWER RECEIVER 5 PACK - BLEMISHED
This 5 pack of AR 15 80% Lower Receivers in the raw is ready to be "drilled and milled" and become the first step towards your next build. No FFL required.alwaysarmed.com