An iodine flask has a conical (Erlenmeyer-shaped) body with a narrow neck and is fitted with a ground glass stopper. The narrow neck helps to minimize the loss of iodine vapors, which are volatile in nature. It is usually made of borosilicate glass, providing resistance to heat and chemicals. The stopper ensures the contents remain airtight during reactions. This flask is widely used in redox titrations involving iodine, where accurate results are required by preventing evaporation and contamination.