Designed to fit BT8390 mounting rails to BT8380 support columns, the BT8380-JPK is a joining plate which is needed to assemble System X freestanding, mobile or bolt-down video wall solutions. The plate is fitted quickly and easily using the provided sliding nuts and countersunk screws, which allow the mounted rail to be positioned anywhere along the length of the column. A row height spacer (BT8390-SP) is also available (separately) to help position multiple rails when installing video walls, without needing to measure out the position of each BT8380-JPK.