Another way to increase the channel density is to reduce the size of the elementary structure. This allows for more cells in a given surface area, and therefore more channel width. However, as the cell size shrinks, it becomes more difficult to ensure proper contact of every cell. To overcome this, a "strip" structure is often used (see figure). It is less efficient than a cellular structure of equivalent resolution in terms of channel density, but can cope with smaller pitch. Another advantage of the planar stripe structure is that it is less susceptible to failure during avalanche breakdown events in which the parasitic bipolar transistor turns on from sufficient forward bias. In the cellular structure, if the source terminal of any one cell is poorly contacted, then it becomes much more likely that the parasitic bipolar transistor latches on during an avalanche breakdown event. Because of this, MOSFETs utilizing a planar stripe structure can only fail during avalanche breakdown due to extreme thermal stress.