Mr. lybrate-user, There is brand by name "Mixtard 30/70 InnoLet 3 ml injection. Usually concerned company persons do visit and explain how to use the Insulin Pens. So while buying it from the local chemist ask him to send the particular company representative to demonstrate the usage. The cartridges are 3 ml while vial is bigger. So please get all the details before switching over. Pens are definitely much easier to use. Thanks.