Updated: May 17, 2020
If you are wondering why Cambium Motorola made the e500, e501, and e502 here are the differences and the reasons:
E500 is really built for heavy-duty outdoor usage with spherical radio coverage and you can mount another radio or security camera.
E501 is pretty much the same except as above but for the coverage is designed for a more narrow focus of 90-120 degrees, in other words a more narrow focused antennae.
Due its narrow focus the distance of these radios will be for longer distances, maybe up to 40-50% or up to 110 meters, you really should POC and test first.
Best installations-street, or long rectangular pool, or wall mounted. These can also be used for really large density solutions, such as music venues, football stadiums and large meeting rooms using the auto channel and auto power selections on eMaestro.
This is where it is best to well engineer the outdoor designs.