Spacer widths are becoming increasingly larger due to new developments in the field of insulation values. Jambs with a standard thickness of 20 mm are especially suitable for sealing a window opening embrasure. As well as providing an attractive finish, it enables insulation material to continue to be applied to the spacer to be as much as possible. This prevents the formation of thermal bridges. Jambs are delivered as flat-type jambs and L-type jambs as standard. Custom-made corner frames can be produced on request.