Pushers are available in two convenient sizes to fit length between 185mm and 385mm or  285mm and 485mm.  Adjusting the length at 25mm  allowing pusher  to be shortened in order to reduce the length and fit different depths of shelving Mounted at the front  fixing rail of your choice is easy to install and adjust.  There is no need to click the divider at the back, just hook it onto the back-rail and fix it to the front grip.