Thunderhead Broadheads have a patented Slimline low-drag ferrule with scooped out sides for superior penetration. The hardened high-carbon steel trophy tip cuts on impact. Consistent quality - head to head, box to box. A patented lock ring, O-ring blade retention system ensures perfect head alignment and cushions the blade on impact. The .027 thick stainless steel blades are ground, honed and stropped to surgical sharpness. Per 5. Available: 85-grain (1-1/8 cutting diameter) 100-grain (1-3/16 cutting diameter) 125-grain (1-3/16 cutting diameter) Cancer and Reproductive Harm- www.P65Warnings.ca.gov. Type: Fixed-Blade Broadheads.