The International Back to Back Wool Challenge began in 1992 when Richard Snow — a young spinner living in Scotland — developed thyroid cancer. His desire to raise funds for cancer research sparked the challenge's creation — a simple and direct method of shearing a sheep, spinning the wool into yarn and using that yarn to knit a sweater.

More than 20 years later, 10 countries participate in the competition each year. The San Diego Spinners are the only group participating this year in the United States.

"It's a unique and amazing event that we've been proud to be a part of for the past three years," says Beverly Codallos with the Sharp HealthCare Foundation. "So far, this fundraiser has raised nearly $3,000 for the Barnhart Cancer Center and has provided much needed support for cancer treatment options here in the South Bay."

Members of the San Diego Spinners collectively knit a sweater at last year's International Back to Back Wool Competition.

Handcrafted items are available for sale throughout the event; all funds raised are donated to Sharp Chula Vista Medical Center's Barnhart Cancer Center.

This story was updated in May 2017.