When you are using a sectional warp beam, you wind the warp direct to the beam in sections. A sectional warp beam is a standard beam mounted with four rails, which have metal loops every two centimeters (or 1") for dividing the warp into sections. The measure around the sectional warp beam is 75 cm (29 ½"). Rails are also available separately. For sectional warping a tension box is needed to keep the warp threads taut and in order.