Torque is usually the most important specification under consideration as larger diameter boreholes are often required. Depending on the depth, the weight of the rig and/or the ability to anchor the unit can be vital. However, the size of the equipment is frequently a limiting factor for micropile drilling. Compact rigs are required to drill in dense urban areas, confined spaces and on low headroom sites. Here again, the ability to drive casing and drill simultaneously is advantageous. Managing size and power (torque in this case) can be difficult for the buyer. Limited access drilling units are often limited in their power capabilities so torque should be noted before purchasing.