These bars only come with a cross bar slot on each stretcher bar at the size of 30" or above. They are easy to assemble, solid and a guaranteed high quality product. Please note that some people get confused by the unusual square end of the stretcher bar. Just slip the bars together as shown in the diagram for the perfect snug fit.
Art Supplies from Jackson's | Jackson's : Stretcher Bars: Jackson's : Alu-Pro : Stretcher Bars and £5 - £10 | Jackson's Art Supplies - Jackson's Art Supplies - Finest Art Materials - Best Prices https://www.jacksonsart.com/de-de/brands/jackson-s/jackson-s-stretcher-bars/sub-brand/jacksons---alu-pro---stretcher-bars/price-range/%C2%A35---%C2%A310