well they come in various size's and the rate the water flows is depended on the size of the bag and the quality of the water. The size on mine is: 20cm wide and the length on the long side is 44cm and the shorter side 33 cm. ( i only do metrics's, no ruler in sight with inches on them)

Never really measured the flow. With tap water, usually a slow stream of water. The bigger models are faster, than the smaller ones. With mud from a car track, this will slow down to a drop every 30 second until the millbank is totally clogged up. The drops however where 100% clear looking.