The light weight High Impact ABS material handles extreme pounding and shearing forces. It contains no metal parts. The exterior is shaped like bones. This is the full sized knuckle unit. Slide it across four fingers in an instant. Easily concealed, fits adult sizes. Overall Length: 5.01 Inches. Finger Hole Size: 1.1 Inches. Material: High Impact ABS. Thickness: 11.3mm. Color: Flat Black.