We had  the extrusion tooling made for this material.  We use this for  spacers for the supercharger kits. Have also used it for radius rods for various applications and threaded bungs. 

The OD is .875 and the ID is .378-.380. Perfect slip fit for 3/8 bolts  and very easy to drill for anything larger like 10mm common in new cars. NO drilling solid bar stock. Just cut and face in lathe or use a parting tool and do the cutting and facing in one operation. Some 12' long pieces are available but most is stocked in 6' long lengths for bar feeding purposes. Material is 6061-T6 extruded. Mill finish but polishes easily prepping with 400 grit and then buffing.   Box of misc drops are sometimes available. Usually 1-4" long pcs.