A device is provided for delivering fluids to, or removing fluids from, one or more fluid streams, the device having a body having a plurality of channels extending through the body from a first to a second end of the body, the body having one or more internal passages therein extending in a direction crossways to the plurality of channels. Each channel is in fluid communication with one or more of the passages via a porous wall between the respective channel and an associated passage. The one or more passages are in fluid communication with the exterior of the body.