Of slack from the rail to the chain (check your manual). http://io.Basnet.byyf0dby0l56lls-9rw.3pco.ourwebpicvip.comn.3@www.theleagueonline.org/php.php?a%5B%5D=%3Ca+href%3Dhttp%3A%2F%2Fxilubbs.xclub.tw%2Fspace.php%3Fuid%3D1977492%26do%3Dprofile%3EGarage+door+Repair%3C%copyright%3E%3Cmeta+http-equiv%3Drefresh+content%3D0%3Burl%3Dhttps%3A%2F%2Fclassifylist.com%2Fstory19772937%2Fgarage-door-repairs-and-set-up-entry-garage-doorways-of-tallahassee-fl+%2F%3E