The DIY Base Vapor Flavour is probably the best base available on the market.

This DIY Base 175ml 30/70 is made in Switzerland, the perfect compromise between flavors and steam it is composed of 30% propylene glycol and 70% vegetable glycerin and provides a hit in throat and will fit the majority of sprayers and clearomizers.

Delivered in a bottle of 250ml containing 175ml of base, it allows to have the place to add the concentrate.