Go to the Laticrete web site to get the final word. But this is what I understand. SpectraLock is an epoxy grout, meaning that it has a part A and a part B that is mixed (like epoxy) and then the colored sand is added. It is durable and stainproof. There are 2 formulations of SpectraLock, the Pro (at Lowes) and the Pro Premium. I have heard that while they are both epoxy there is a slight difference in the color out come and they should not be used next to each other (in the same grout job) because the grouts will be slightly different in color. I have also heard that the Pro Premium is supposed to have better spreadability.

Laticrete has a regular cementous grout product called LATICRETE PermaColor. I do not think that Lowes carries this any longer. I have heard from Bill V. on this site that this is a very fine product.

I have just finished grouting my slate bathroom floor and used the SpectraLock Pro Premium that I ordered online with great success. The site I ordered from was linked on the Laticrete site as a distributor. This is their web site and I was very happy with the packing and shipping time frame.
http://www.tilestoreonline.com/default.asp
I got the "full unit" without the bucket for $43.70. I can't remember if shipping is free. Anyway, got the grout, and with my 1/4 grout margins, I got about 45-50 sf out of this "full unit" - about what I predicted using Laticrete's grout estimator.

I have read that epoxy grout is hard to use for some people. I did not find it to be difficult, but I don't have much to compare it to. I followed the instructions to the "T". Except I learned on the JB forum from a poster, that you can freeze the epoxy and take it out later for patches. So, I took a zip lock bag and put about a 1/2 cup of the grout in to it, smashed it to about the thickness of a pancake, zipped it shut, and froze it. A few days later I found a few divots in the floor where my toes or fingers may have pushed in, as I was grouting. I broke of some pieces of the frozen grout and it thawed very quickly. I smeared it into the imperfections, then waited 20-30 minutes. I then went over it with a damp sponge rinsed and rung out in a few cups of H2O mixed with a few TBS of white vinegar. In other words I used the same cleanup procedure that I was instructed to do with the initial installation of SpectraLock. Except I didn't have the "rinse" product. I had read on the JB forum to use vinegar in the water and this will work as a rinse. After it fully dried I could not see any difference between the small patches and the original installation.

I plan to use SpectraLock Pro Premium on my walls too when I get them tiled.

Here is a link that might be useful: Laticrete web site