Safety alarms designed to attract attention and scare off unwanted sexual advances are being distributed to vulnerable Rohingya women and girls, who make up the majority of refugees in the sprawling tent cities in Bangladesh.
A piercing wail emanates from the small device in the palm of a young Rohingya woman, drawing startled looks from other refugees crowded onto a hillside in a Bangladesh camp.
It has the desired effect - the safety alarms are designed to attract attention and scare off anyone preying on vulnerable women and girls, who make up the majority of refugees in the sprawling Rohingya tent cities.
The colourful plastic sirens are being distributed to Rohingya women, girls and the infirm in Cox's Bazar district, where an estimated 655,000 of the Muslim minority have arrived since August.
They have escaped a systematic campaign of rape and violence in Myanmar described by the United Nations as ethnic cleansing - but the squalid camps across the border are not without dangers.
Aid groups say women and girls, many of whom have arrived in Bangladesh alone, are at particular risk of exploitation by pimps and human traffickers active in the camps.
The alarms, fitted with a torch and high-pitched siren, provide comfort for Rohingya women like 22-year-old Hazera Khatun, who frets constantly about the safety of her two daughters.
"I feel safer and less scared now after receiving this, because now I know that if I encounter any problem, I can call for help," Khatun said, gesturing to the device in her hand.
The local charity behind the alarms, Moonlight Development Society, developed the idea after hearing about abduction attempts on young children in the camps.
Since then, they have distributed nearly 1,000 alarms to refugees - mainly women and children, but also the elderly and others vulnerable to abuse.
TRT World's Joseph Hayat has more on the story.