Sir Paul McCartney is auctioning the boots he wore at the 2012 London Olympics opening ceremony to raise money for the Meat Free Monday campaign.

The boots will be sold by Sotheby’s for between £10,000 and £15,000, according to auctioneers’ estimates.

“As the time came to buy myself a new pair of boots, I thought this might be a good way to help our Meat Free Monday campaign celebrate its 15th anniversary,” said the former Beatles member.

“My boots and I have great memories of that special night at the London Olympics opening ceremony. It was great to participate in such an awesome and spectacular event. Something I will remember forever,” he emphasized.

The English singer and musician started the non-profit campaign with his daughters Mary and Stella McCartney to encourage people not to eat meat one day a week. “One plant-based meal a week is a fun and easy way to do something good for the planet and our future” is the central message of the campaign.

Sir Paul McCartney’s boots are similar to the ones he wore when he was in the Beatles and are made without the use of animal-derived materials by Anello and Davide, a company specializing in theater footwear.

The auction is organized by Sotheby’s on May 24 – 31 and will be exhibited at its gallery in London.