The ultimate examples of such design are single-use versions of traditionally durable goods, such as disposable cameras, where the customer must purchase an entire new product after using them a single time. Such products are often designed to be impossible to service; for example, a cheap "throwaway" digital watch may have a casing which is simply sealed in the factory, with no designed ability for the user to access the interior without destroying the watch entirely.[citation needed] Manufacturers may make replacement parts either unavailable or so expensive that it makes the product uneconomic to repair. For example, inkjet printers made by Canon incorporate a print head which eventually fails.