Flexible nylon accordion dust cnc machine bellow covers Folded cover We manufacture folded covers to suit your specific machine. Get a reliable solution that provides complete protection day in and day out. We always guarantees the highest quality and fast delivery times in order to reduce costly production stoppages. Choice and models Folded covers, or concertina covers as they are also called, can be placed horizontally, vertically, and intersecting. Another type of concertina cover is used to protect against crushing injuries at lifting tables in an assembly line, for example. This cover protects on four sides and has welded corners. Just like our other models, these also have PVC supports for added protection.