Yes, participation is mandatory for all sellers. The service offers sellers a number of advantages: We cover the cost of insured shipping to the watchmaker and provide the seller with a free shipping label for this purpose. We also provide insured shipping from the watchmaker to the buyer following certification. Sellers are protected against unjustified complaints, as the buyer has no reason to complain about the watch after it's been certified. If the package goes missing during transit, we will take care of everything else. Certified watch listings are more attractive to potential buyers, as certification gives them an added layer of security.