Grids are available in 12-column, 16-column and 24-column flavors.
12-column grids
12-Column Grid 01
The 12-column grid is dividable by 2, 3, 4 and 6, which is enough flexibility for most projects. This particular grid system has a 1% gutter between columns, and 20px vertical spacing between rows. The breakpoint is at 600px.
12-Column Grid 02
Another variant on the 12-column grid, this one has 2% gutters and a breakpoint at 750px.
12-Column Grid 03
5% column widths, 3.6% gutters, 1000px breakpoint, 40px vertical spacing between grid rows.
16-column grids
16-Column Grid 01
The 16-column grid is dividable by 2, 4 and 8. The column width is small enough that whole columns can be used empty as extra guttering. This grid has 0.5% gutters and 20px spacing between grid rows. The breakpoint is 750px.
16-Column Grid 02
As above but with wider 1% gutters.
16-Column Grid 03
As above but with 2% gutters and a breakpoint at 900px.
24-column grids
24-Column Grid 01
The 24-column grid is the most flexible. It is dividable by 2, 3, 4, 6, 8 and 12, providing lots of flexibility in the presentation of content. This 24-column grid has 0.5% column gutters, 20px between grid rows, and a breakpoint at 750px.
24-Column Grid 02
As above but with 1% column gutters.