Or as this article eloquently puts it, "WTF is an interlabial tampon?"
According to the article, "The Interlabial Pad is kind of a cross between a pad and a tampon. The pad is worn externally and are used for both menstruation and for light bladder leakage. They are leaf-shaped and worn length-wise between the labia. They come in various shapes and sizes and can be washed and reused."
The manufacturer states that the pads are meant to be kept between the lips of the vagina to "catch the menstrual flow much closer to the vagina to avoid messy leaks during heavy flow/flow with clots. It stops the blood from rushing out, instead regulating the flow from the vagina towards the center of the pad. It sort of wicks the flow."
A woman who reviewed the product said "I was pleasantly surprised with the results because it DID take care of the gushing. However, it may take me some time to get used to it, because the feeling of something constantly there between your lips can feel weird."