Estes Marine Sand 50206 to be exact. Their pdf aquarium gravel catalog is found here: http://www.estesco.com/pdf/aqua.pdf It is expensive but nice, I have a DSB and it does require allot of work. In my next tank I will be going with a larger grain and one that does not compact as easily. Pool filter sand is nice also.
I use PFS and I like it a lot. My sand bed is probably 1" though it's variable because the fish dig in it and move it around. I used 100lbs for 9 sq ft of tank bottom, cost $16