These flasks are the choice for general laboratory usage. Tops are reinforced and tooled with a rounded finish, containing more glass to give them maximum mechanical strength. Body is thick walled with a long tapered outside contour to minimize chipping when struck or rubbed together. All flasks have durable white ceramic enamel scales to indicate approximate volumes at various levels, useful in measuring and mixing solutions where a high degree of accuracy is not necessary. Designed from ASTM Specification E1404, Type I, Class 1 requirements.