Glass milk bottles are glass bottles used for milk and are generally reusable and returnable. Milk bottles are used mainly for doorstep delivery of fresh milk by milkmen: retail store sale is available in some regions (with bottle deposit). After customers have finished the milk they are expected to rinse the empty bottles and leave it on the doorstep for collection, or return it to the retail store. The standard size of a bottle varies with location, common sizes are pint, quart, Litre, etc.