LEIFELD UniBlock
The LEIFELD UniBlock was developed to provide a torsion-proof and easy method of securing double wall-elbows (also accepts single wall-elbows) at the standard sanitary centers (80, 100, 120, 153 and 160 mm) in drywall constructions.
And, on this page, two further products (mild steel) for mounting wall-elbows in pairs - LEIFELD Mounts