A lou is composed of rack, funnel, leg, and plough. The rack is made of wood and usually drawn by an ox and handled by a person. The funnel has two cells, one big and the other small. The big one contains seeds; the smaller one is connected to the seed flow-adjusting door to drop seeds evenly down. Its leg and plough are of iron spade and handle to cut open the soil.

Seeding width and lines vary. Accordingly, a lou can be one-, two-, three-, or four-legged. The three-legged lou works best as it can perform several functions all at once such as tilling and seeding.

The lou was developed two thousand years ago during the reign of Emperor Wu of the Han Dynasty. It is the world’s earliest seeding tool.