This specification provides standard dimensional requirements for glass conical flasks suitable for general laboratory use. Conical flasks (Erlenmeyer) shall be classified into four types which are divided into classes. Type I is for general purpose with graduated scale and shall be designated into two classes: Class 1 with narrow mouth and heavy duty beaded top and Class 2 with wide mouth and heavy duty beaded top. Type II flasks have tapered ground joint with graduated scale. This type shall be divided into three classes: Class 1 with outer conical, joint without stopper, Class 2 with stopper and Class 3 is used for iodine determination. Flasks of Type III have screw thread finish, with graduated scale. Lastly, Type IV flasks are used for culture and they are differentiated into three classes: Class 1 flask has long neck, plain top, Class 2 has wide base (Fernbach), and Class 3 has also wide base and low form. The flasks shall be made of borosilicate glass.