Volunteers from all over the country are knitting cosy inserts for women who have had a mastectomy.
About 3300 women are diagnosed with breast cancer each year. For men, it is about 25 per year.
Chris Finlayson, from Northland, is part of Knitted Knockers and is a breast cancer survivor herself.
She told Seven Sharp her husband Jock got her into the movement, handing her a pattern after he had got wind of it.
Since then, she has done about seven hundred knockers.
"I can do one in a day now, depending on what's on TV."
Jock does the advertising, encouraging those with breast cancer to get in touch with Chris.
The pair have women regularly drop-in for fittings.
"It's just another way of making people happy," Finlayson said.
The clack of knitting needles can also be heard further south at a retirement village in Pukekohe.
It is here Cora Brooking knits Knitted Knockers, including for happy customer Pat Mravicich, who had a double mastectomy.
"I put my bras on, fit them in and off I go," she told reporter Carolyn Robinson.
Mravicich said her Knitted Knockers are "lovely and soft" to wear.
More traditional breast prosthetics can be hot and heavy, Breast Cancer Foundation's Debra Leutenegger said.
"Some women don't find them very comfortable," she said.
"Especially post-surgery, you have a wound that is healing, it's not the right thing to be putting a more permanent thing into that region.
"The knitted knockers are just nice and soft and caring."