Fixpandable 100gr Broadhead 4pk Plus Practice Head Shoot a FIXed blade + an expandable blade in one broadhead! Ferrule Material: 6061-T6 Aluminum Blade Material: 420J2 Stainless Steel Nose Blade Thickness: 0.047 Expandable Blade Thickness: 0.031 "O" rings are weather resistant, low memory material rated to perform in temps from 130 degrees to 45 degrees below zero