Got this from the web:
"Advanced aerospace manufacturing technology and a highly skilled staff are utilized to produce the industries finest, forged Mil-Spec lowers. Our receivers are machined on a multimillion dollar, automated, cellular manufacturing system which enables us to produce a product of unequaled quality and value.
These forged lowers will accept all standard lower parts kits. These have pictograms for fire control and are quality made using 7075 T6 aluminum and are marked "CAL MULTI" to accommodate most builds."