A panel can have a face surface having a length and a width. The panel can include a first tongue that extends along the length and a second tongue that extends along the width. The panel can further include first front and back legs that extend along the length of the panel and define a first groove therebetween and second front and back legs that extends along the width of the panel and define a second groove. At least one of the first tongue or the first back leg has a longitudinal dimension that is greater than the length of the face surface; or at least one of the second tongue or the second back leg can have a longitudinal dimension that is greater than the width of the face surface.