This product was designed to assist individuals with dupuytren's contracture. The simple design converts a regular tap that might be difficult to use into one that can be operated with a simple push or pull using a closed fist. In turn, this significantly reduces the dexterity required to operate it.
The design is easily installed by sliding it onto the tap, where the two arms grip onto it via a ribbed surface. The initial version didn't provide enough grip to turn the tap, and so a strip of blue tack was introduced on the ribbed surface to improve its grip (I didn't have any rubber to hand which would be used if it were mass produced, but they should both perform similarly).
Rather than having to replace all the taps in ones house, flow offers a low cost alternative that can be fitted onto taps of a range of diameters. Alternatively (if 3D printed) the design can be quickly adjusted to suit your tap configuration. Its use is shown in the following video: