These collars have the soft texture of leather, but they are stronger, more durable, easy to clean and come in fun colours.
Biothane is an extremely durable and resilient waterproof material so it requires little in the way of maintenance to keep it looking bright for a long time, but there are a few things you can do to help prolong the life. Regular cleaning with a gentle detergent and an old toothbrush can tackle most spots and dirt with ease - for the tougher stains, I recommend using a dab of rubbing alcohol in addition to the earlier mentioned items. Tarnish that has transferred from the metal hardware onto the biothane may require some additional scrubbing/muscle to remove, especially if intervals between cleaning are long.
While biothane is an incredibly versatile material that can withstand MOST of the dirt and grime it comes across, please note that it is not completely stain proof in all circumstances.