Having used a variety of Vype e-devices over the years I have settled to using the pro and pro2 tanks which have a better suction draw experience, are less likely to leak and are easier to clean than the cheaper devices. If asked what improvements I would like they are,in order 1- A fluted mouthpiece so it is possible to hang on to the tank with my teeth while using both hands. 2- A variety of coloured mouthpieces to help me keep track of the order of use and life of atomiser. 3- A rubber sleve to fit around the glass tank section to help it survive the inevitable fall to the floor, I use different coloured rubber bands treble looped which have saved the glass tank on more than one occasion and help me identify the device.