Approximately 22mm wide, - This is two layers of strong polyamide tape which have been sealed together, with tram lines running down the sides for your stitching to follow. It is a tubular channel tape, which once sewn on, the bones can easily be slid in, the actual channel is about 13mm. Unlike making your own casing this is smooth and flat. The great advantage of using this is it can be sewn on the coutil lining of a corset so that no bone channel stitching shows on the outer of the garment, or, sewn on the inside of a single layer corset giving super strong channels and a professionally neat finish on the inside. Ideal for 11 - 13mm bones. We have found the white tape dyes very sucessfully.