What size filters would i need on these lens?

Http://www.amazon.com/Sigma-70-300mm-Nikon-Digital-Cameras/dp/B0012X43P2/

http://www.amazon.com/...0012UUP02/

http://www.amazon.com/...000O161X0/

I also have a question… Are these all auto focus lens? My d3100 does not have an auto focus motor… And which would set of lens would be best for outdoor daylight water sports photography.

Added (1). I wanted to know which filters would fit. Like 52mm? 62mm?

For future reference, ANY Nikkor AF-S lens has an auto-focus motor in it.

There's also a Nikkor AF-S 55-300 mm lens you may want to include in your research.

Generally it is best to buy within the Nikon lenses when buying a second or third lens

Found the filter sizes easily in the specifications section for these lenses at www.slrgear.com:

Sigma is 58mm
Tamron is 62mm
Nikkor is 52mm

The Nikkor 55-200 may not have quite the reach of the other two, but the Image quality is FAR better. I'd get that one.