These adjustable curves are meant to take the place of french curves and other rigid templates used to draw curves. 12 interlocking layers of butyrate slide past each other as you shape them to match a series of plotted points (or the curve you're imagining), then friction holds them in place. Unlike flex rules made of lead, ACU-ARCs can only be bent into fair shapes, never kinking. If the individual strips making up the curve ever come apart, finger pressure will reassemble them. Manufacturer suggests storing out of sunlight.