All of Ryan Lochte’s Olympic silver and bronze medals are auctioned off, with proceeds going to a charity to benefit children.

The 37-year-old swimmer has won 12 medals in four Olympics, including six golds which he intends to keep for now.

“I’m not one to be sentimental about medals,” Lochte told The Associated Press by phone Sunday after a vacation in Mexico. “My medals are just in my closet gathering dust. The memories I have are what matter most.”

The medals are being sold in three lots by Boston-based RR Auction. Sale ends July 21.

The first batch is Lochte’s first individual Olympic medal, a silver in the 200 meter individual medley at the 2004 Athens Games in which Michael Phelps won gold. It has an estimate of $10,000 or more.

The second batch is a pair of bronze medals from the 2008 Beijing Games, where Lochte finished third in the 200 IM and 400 IM. The estimate is $12,000 or more.

The third batch includes three medals from the London 2012 Games. Lochte was second in the 200m individual medley, second in the 4x100m freestyle relay and third in the 200m backstroke. The estimate is $60,000 or more.

Bobby Livingston, executive vice president of RR Auction, said the medals were presented by someone who received them from Lochte and wished to remain anonymous.

“They’re in perfect condition. They have beautiful ribbons,” Livingston said. “Ryan’s are obviously extremely interesting for medal collectors.”

Lochte confirmed that he was not the direct seller.

“I gave them to a third party,” he said. “Everything we earn goes directly to the charity.”

Also on sale are a 14k white gold Olympic ring and a Breitling watch with black diamonds. Lochte bought both items for himself after the London Games.

His selected charity is the Jorge Nation Foundation, a non-profit organization that raises funds to send terminally ill children and their families on a dream trip from South Florida to a destination of their choice. Lochte said he has worked with the foundation for more than 10 years. Its agent is part of its board of directors.

“This year I really wanted to focus on giving back. I love it,” he said. “I team up with my dad for swim clinics and go out with my own sunscreen.”

During his career, Lochte regularly distributed his medals from national competitions to children in the crowd.

Lochte hasn’t competed in a major competition since last year’s US Olympic Trials. He was not part of the Tokyo team. Last month he raced in an ocean swim in the Cayman Islands and finished 14th.

“A mile in the ocean is very different from a mile in the pool,” he said. “I swear I thought I was going to have a heart attack.”

He plans to lose some of his six gold medals in the future. He wants to keep his first individual gold medal in the 200m in Beijing and another for his father, Steve.

“These medals mean a lot to me; I worked my [rear] for them,” Lochte said, “but helping others is more important to me, especially because I have children of my own.”

Lochte’s 12 medals are tied for second among swimmers, behind only Phelps’ Olympic record of 28.