Cylindrically shaped with a flat bottom and graduation markers, beakers come in either low-form or tall-form heights. Low-form, or standard, beakers usually have a height that is approximately 1.4 times their diameter, while tall-form beakers are approximately twice the height of their diameter. Unlike flasks, beakers have straight sides. Beakers are generally made of borosilicate glass, however, beakers produced from metal, polyethylene and polypropylene are also available. Beakers may also have a small spout or beak to aid in pouring.