Three widths of Sarel Aerators are available. Aids water / air penetration, greatly improves root growth, for use when seeding and general turf maintenance. Each large spiked section is 11? in diameter, calculated to avoid ?tearing? of the turf. The tensile steel spikes are 1/4? in diameter, and 1 1/3? in length. Each spike is replaceable, held on with a large nylock nut. Also coupled to each unit is a 4.1/2? diameter roller for transportation across hard surfaces and for use as a ground rolling tool.