Springs butt to each side of corner. This is the most common corner configuration.
In addition to the springs on each side of the corner, there is an extra spring mounted diagonally. These extra corner springs are typically longer than other springs.
Each corner has only a diagonal spring with no additional springs on each side of the corner. These corner springs are typically longer than other springs.
Springs are spaced evenly along the mat's sides except close to corners. Beside each corner, the first three springs are crowded together.