This is the APC 16x8 Thin Electric Propeller. APC propellers are manufactured using a pultrusion process which allows for a higher fiber (60%) to resin (nylon binder) density. This provides substantially higher strength and stiffness than glass-filled nylon. The additional stiffness is beneficial to control vibration resonance response. The higher strength allows the use of thinner cross-sections, beneficial to weight and aerodynamic efficiency.