Spacer for insulating glazing units

A spacer for an insulating glazing unit, comprising:

• a polymeric main body comprising:
• a first pane contact surface;
• a second pane contact surface parallel to the first contact surface;
• a first glazing interior surface;
• a second glazing interior surface;
• an outer surface;
• a first hollow chamber;
• and
• a second hollow chamber,
• wherein:
• a groove between the first glazing interior surface and the second glazing interior surface configured to accommodate a pane runs parallel to the first pane contact surface and the second pane contact surface,
• the first hollow chamber is adjacent the first glazing interior surface, and the second hollow chamber is adjacent the second glazing interior surface,
• lateral flanks of the groove are formed by a wall of the first hollow chamber and a wall of the second hollow chamber, and
• a web is arranged directly below the groove on a side of the spacer opposite the groove.