Wunderbars DEEP - Packs of 4 Available in the following sizes 10", 12",16", 18", 20", 24", 30" These bars are 42mm deep compared with 32mm of the Tulip and White Wunderbars. Wunderbars is a revolutionary framing system for creating canvas wraps. These easy to use bars provide a quick and simple solution for stretching canvas without the need for specialist tools or skills. The unique design of the bars, ensure that regardless of the hanging environment the canvases will remain under constant tension, eliminating sagging and rippling. The wood used for Wunderbars are Tulip wood and Scandinavian Pine from sustainable sources, which are FSC and PEFC certified. Wunderbars constant tension stretcher bars are easier to construct and stretch than traditional stretchers. Each bar is precision machined so that when the frame is put together it is square eliminating the need to constantly keep tapping it to keep it square before stretching. Unlike other stretching systems there is no need for expensive machinery or devices, the only tool needed is a staple gun. Wunderbars’ unique self tensioning corner blocks ensure, there’s no more sagging canvas, it always stay taught and will contract and expand to the room’s temperature and humidity. The special tensioning corner blocks eliminate the need for wedges making for a cleaner finish on the rear of the frame. Due to the way Wunderbars work the frames can be re-used by stripping off the old Canvas and re-setting the corner blocks by reinserting the holding pin.