It can also be used to enhance pleasure.
They use a silicon based ring that is inserted into the vagina.
The ground breaking ring contains HIV preventative drugs and requires monthly replacement.
It is similar to a diaphragm (the birth control measure) but this ring releases an anti-retroviral drug(ARV) called dpirivine for a month.
It can't be felt by a partner but should it, reports from tests in the US show that it enhances pleasure.
Clinical trials are ongoing in Malawi and results so far indicate that 1 in 3 women are safe- which is better than nothing as negotiating for a condom has proven difficult with male partners.
It will get worldwide supply once it gets medical approval.