Carbon Express 51520 Maxima Blue Streak Select Carbon Target Arrow Shaft Bare shafts come with LAUNCHPAD Precision Nocks, Bulldog Nock Collars and Screw-In Inserts (nock color may vary from image) Dual Spine Weight Forward - patented fusion of two different carbon materials that creates 2 spines in 1 arrow Laser checked for straightness to a remarkable 1/10,000 of an inch; Straightness of +/- 0.001-inches is a maximum measurement, not an average Item specifications: 350-Size, 8.3-GPI, 0.347-inch Spine and 0.295-inch Diameter 12-pack of black finished shafts are sorted and matched by weight and spine for best-in-class consistency