For more information about the river aerators, check the mega aerator page, where you can find a full explanation. The river aerator is available in 4 sizes, the model numbers of the river aerators correspond to the last 4 or 5 digits of the mega aerators. The difference between the river aerator and the mega aerators is the aeration direction. The river aerators aerate in one direction and works best when the water flow is passing along the unit. The mega aerator aerates in multiple directions and doesn't require a natural or artificial flow.
For technical details, check the specs on the right side of the webpage or check spec-sheet full tables: