The share is the edge that makes the horizontal cut to separate the furrow slice from the soil below. Conventional shares are shaped to penetrate soil efficiently; the tip is pointed downward to pull the share into the ground to a regular depth. The clearance, usually referred to as suction or down suction, varies with different makes and types of plough. Share configuration is related to soil type, particularly in the down suction or concavity of its lower surface. Generally three degrees of clearance or down suction are recognized: regular for light soil, deep for ordinary dry soil, and double-deep for clay and gravelly soils.