Also Known as Ground saw, easy trencher, easy trench, e z trench, walk behind trencher

The ground saw will trench 100 feet in approximately 5 minutes. Replaceable heavy-duty carbide bits and all steel construction make it very durable and dependable. The on-the-go depth adjustment enables the operator to dig a trench 2 ½” wide from 0 to 13” deep with ease. It is ideal for installing irrigation, propane gas lines, silt fence, etc…

Features:
Round Steel Blade with Replaceable Carbide Bits
Progressive small bites cut hard clay soils and roots. Carbide bits have excellent wear factor.
Compact and Lightweight
Easy to transport and operate.
Depth Adjustment Crank
Easily adjust depth from 0"-13". 
Pneumatic Tires
Stable and easy to roll.

Source: E-Z-Trench