Mechanical Cross Bars are recommended for any stretcher with dimensions over 100cm in length. They keep the stretcher construction rigid and provide extra strength and support. Cross Bars are double notched after 100cm.

The cross bars simply slot into the stretcher bars via the mechanical ovals. Screws are inserted into the mechanical  ovals after stretching your material and simply turned to increase the size of the stretcher for the perfect tension.  

34mm Mechanical Cross Bars (single)