Lowrance struct. Scan or HD Module whats the difference?

[BigPapa]

So Im wondering whats the difference of these two modules that I see on Tacklewarehouse.
I know one of them comes with a transdeucer, for $999.

But the other says HD not Structure Scan 3D
http://www.tacklewarehouse.com/Lowrance ... SSIHD.html

[Edd]

There is a huge difference between HD and 3D. You may not find a need for 3D but, the 3D module gives you more side-2-side area to view. If your budget can stand a few hundred more, go with the 3D. If not, the SS-HD will work great, especially with the latest 'FishReveal' upgrade.

[BigPapa]

Do the "Carbon" series need this module also or No??

[Edd]

3D requires a module but SS-HD is built into the Carbon. You can always add 3D if you decide you want that feature.

[BigPapa]

Thank you! Now just gotta make up my mind which one to buy