- Rooster spurs 20 mm or 30 mm. Made of stainless steel by Sprenger. It has a built-in rubber protector to prevent the boot from rubbing. Color: Black. Supplied without strap 20mm or 30mm cock. Made of stainless steel by Sprenger. It has a built-in rubber protector to prevent the boot from rubbing. Colour: Black. Supplied without strap