Trying to do your yard or have some other idea with it?
If your trying to do your yard, find one that has hollow prongs and pulls out plugs in your yard, it is a lot more effective with aerating and allow the soil to breath, makes a big ole mess with plugs all over your yard. An aerator like the one pictured packs down the soil more and pushes it in if you know what I mean causing less air to get to the soil and roots.
I might have an old one you can borrow. I'll look when I get back to the storage building.