Abstract: The present invention is a fastener assembly, and a system including two panels secured together by the fastener. The panels may form part of a container with two portions secured together by the fastener, such as a door and a panel to which the door is hingedly connected. The container may have walls that are formed of a composite material with a metal edge channel. The fastener is suitable for joining panels that are relatively thick, such as those formed of a composite material. The fastener includes a screw rotatable in a body to move a crossbar into engagement with one portion of the container to clamp that portion to another portion of the container. The fastener is tamper resistant and operable completely from the exterior, without need to access the inside end of the fastener.