Manual aerators usually have two to five hollow tines mounted on a step bar. The operator puts one foot on the step bar and push it downward, forcing the tines to penetrate into the soil. Then he pulls the handle on the step bar upward to remove the soil cores out of the ground. By repeating the same operation, the cores left in the tines will be pushed out by the next ones. Manual aerators are much cheaper than powered ones. The trade-off is the speed. For a typical residential lawn (1/4 acre lot), it will take hours to finish. Some products also have issues with the tines becoming clogged with soil, which can slow down the operation even more. However, a well-made manual aerator offers advantages such as ease of use, selective aeration, and economy.