Nb frame is an innovative aluminum stretcher bar system for professional artists, museums and restorers. its patented design creates a perfect framework for canvas stretching, free from deformation, twist and warp caused by humidity or dryness. the nb frame system is available in 3 m profile lengths with separate assembly parts, and in pre-cut lengths. all in frame depths of 25 and 45 mm. pre-cut stretcher bar pairs come with 2 x cannbub20 corner brackets and screws.