Pioneered by Richards-Wilcox and manufactured to rigid U.L. requirements, fusible links provide a heat activated mechanism that assures positive closing of doors, windows, hatchways, dampers and blowers. The links fuse when their rated temperature is reached, releasing the open door to block the path of fire. The load is equally spread over all links such that the door will be released even if only one link fails. Note: Links should not be painted, since this will alter the fusing temperature. Also individual maybe used only for weights up to the specified capacities and with a straight pull. If links are subjected to loads in excess of this rating or if used in a manner other than a straight pull, they may break, endangering people and property. To insure the safest door operation links should be replaced annually. Richards-Wilcox specifically disclaims any warranty if the above conditions are not met.