Saddle bar
A saddle bar is a horizontal bar of metal, usually iron or bronze, fixed across a window opening to support the leaded glass. The leaded panel is attached to the bar with copper wire or lead ties that are soldered to the lead came and twisted around the bar.
Leaded lights are flexible and heavy, so without support a tall window will bulge and sag. Saddle bars are spaced at intervals up the window, and in medieval windows they are also visible as the straight horizontal lines across the design, which the glaziers allowed for by planning their designs around them.
In restoration, saddle bars are often one of the first things to be checked, since a corroded bar can break the glass around it.