In what must be some kind of record for soliciting infant head cozies, the Oklahoma State Department of Health (OSDH) has put out an open call for hand-knitted baby hats. And not just any baby hats—they have to be purple.

The campaign is part of an effort to raise awareness of Shaken Baby Syndrome, a form of abusive head trauma that's a damaging parental response to excessive crying and can result in serious brain injury. The effort, dubbed "Click for Babies" after the sound knitting needles make, is intended to highlight the potential hazards of improper infant care.

Why purple? Because the National Center for Shaken Baby Syndrome refers to an infant’s period of prolonged crying as the PURPLE period. The word is an acronym for reminders about the syndrome: L, for example, stands for Long-Lasting. Babies can cry for five hours a day, up to four months of age.

Potential donors should choose a washable, soft yarn, with the hat standing 4 to 6 inches high. Due to potential choking hazards, decorations are not recommended.

OSDH will be collecting caps through October 1 and the knitwear will be distributed to birthing hospitals and public health facilities along with a booklet on Shaken Baby Syndrome. If you’d like to donate a hat, you can mail it to any one of three addresses listed on the state’s web site. The program is hoping to receive 5000 hats for the cause. You can also check out the Click for Babies website to see if the campaign is being promoted in your state.

[h/t ABC News]