Billy Goat AE401H AeratorThis unit completely eliminates the conventional and cumbersome center wheel and center drum designs found on other units, which are prone to wear, vibration and damage. Billy Goats outboard drive wheels also eliminate center wheel slip and abuse from ramp loading with the tines engaged. Additionally, the AE401 also eliminates bulky steel weights, in favor of a simple to use water weight positioned directly over the tines for better aeration depth