MabefPainting Revolving Canvas Accessory for Easel, Brown

Instal[ mabef rotating accessory video? enclosed material only shows images, no written instructions. need video; unable to find; annoying.

How wide is the mast on a Mabef easel?

Once the canvas is rotated, can you lock the position of the attachment into place so that the canvas does not move while painting?

How do i know if if this item will attach to my easel ? what makers does it attach to without too much aggravation, as i would have to enlist help...