Coop3422I believe the lens you are trying to describe is the 55-300 DX lens. That lens is built specifically for DX body cameras D3000 series, D5000 series, D7000 series, etc. The lens being sold here is an FX lens, but it will work on both FX and DX bodies. This lens has superior glass and build quality. All around better lens. Faster auto-focusing, this lens will not have the vignetting you may encounter with a DX lens. Especially if you are trying to use a DX lens on an FX body. Highly recommend jumping on board. I have done a ton of research on this lens and couldn't jump on this deal soon enough. Hope this explanation helps.
SimplyTreExcellent, appreciate your detailed reply. I would be buying this for my D3100. I barely use it though which is why it's tough to justify the extra cost. $319 from Best Buy and to be a pretty good price for what it is.