The AX25/40 1" rockwool propagation cube comes in a sheet of 200 cubes, which fits nicely into a standard 10" x 20" greenhouse flat. They are most commonly used for starting lettuce and other leaf crops, and flowers.
They are similar to the AO25/40 cubes, but the hole is simply at the narrow end of the cube.
Cubes are roughly 1 in. x 1 in. x 1.5 in.