Sharon Simpson, 52, was diagnosed with breast cancer in January 2013. And like many women, the Glasgow resident decided to forego reconstructive surgery after her mastectomy.

Simpson is now cancer-free. But during treatment, she stumbled upon Knitted Knockersโ€”a nonprofit that makes knitted cotton prostheses for women who have lost their breasts to cancer. The organization has been providing free prostheses to women since 2011.

Simpson was so moved by the nonprofitโ€™s mission that she joined a team of โ€œKnockerettes,โ€ volunteers who knit about 300 prostheses each month. โ€œBreast cancer isnโ€™t pink and it isnโ€™t fluffy,โ€ Simpson told BBC News in a video thatโ€™s recently gone viral. โ€œItโ€™s a nasty, horrible disease that changes peopleโ€™s livesโ€ฆMy reason and purpose is to make life better for people in the throes of cancer.โ€

Why knitted prostheses? Simpson explained theyโ€™re lighter-weight and more comfortable than the stick-on silicone breasts offered by the UKโ€™s National Health Service. โ€œItโ€™s quite soft,โ€ Simpson said, holding up a knitted prosthesis. โ€œAnd it would be natural if that was in a bra.โ€

The Knockerettes understand thereโ€™s no one-size-fits-all approach to prosthetic breasts, so the Knitted Knockers come in a variety of sizes (and colorsโ€”from multihued brights to subtle skin tones). Customers can buy prostheses with or without nipples, and they can purchase โ€œaqua knockersโ€ to wear when they go swimming.

โ€œWeโ€™ve had feedback from recipients that has made everybody cry,โ€ Simpson said. โ€œWe had one lady who hadnโ€™t worn anything other than big baggy t-shirts. And she got her Knitted Knockers, and she went into her wardrobe, and she tried every item of clothing on that she had, because she looked like she did before the mastectomy.โ€