Abstract: A fitting for transverse joining of two L-shaped sections is provided, each L-shaped section with a web part and a foot part. The sections are disposed with the web part back-to-back, being peculiar in that the fitting substantially includes a first flange and a second flange which are J-shaped and which in mutual contact are slidingly connected with a connection for constituting a largely C-shaped fitting with a gap of variable length for accommodating the two foot parts of the L-shaped sections. The fitting includes means for mutual fixation of the two flanges for retaining the length of the C-shaped fitting after receiving both foot parts in the C-shaped fitting.