Buckle a not only provides a convenient and economic method of product assembly, because of a combination of parts in the production of finished products at the same time when molding, assembly time do not need to coordinate with other lock accessories, such as screws, meson, as long as to combination button on both sides of a cooperate with each other. Although buckle a design can have a variety of geometric shape, but its operation principle are roughly the same: when the buckle two parts, one part of the cusp out part of the edge part by following parts shot away, until end strike edge part; And after, through the elastic and plastic cusp out instant reset, followed by the grooves or when the following parts of edge part embedded invert the position and form of locking status with each other.