Some of these characteristics are defined by Ruch, Fearon and Wieters as follows:
Functionality refers to the performance of the product. It can be measured either on a yes-no basis such as whether a radio works or not or it can be measured on a continuous basis such as how many miles a car goes on a gallon of gasoline.
Reliability can be measured from different angles. Some of the considerations are: i. How long will the product function as claimed, under normal working conditions? (Durational reliability).
ii. Does the product function every time it is used or does it fail to function occasionally? (Functional reliability). iii. If a product has many components, such as a car, with each component having its own probability of failure then what can be said about the probability of failure of the assembled product? (System reliability). iv. Consistency in the level of quality of each successive unit produced by a given process.
Durability involves not only the time period in which the product is expected to function, but also the conditions under which it must operate such as heat, cold, dust, vibrations and so on.
A quality product cannot be shabby looking, even if it functions well. Aesthetic component refers to smoothness of surface, symmetry and absence of dents or scratches.
A high quality product should perform its function without unnecessarily endangering the safety of the user. For example, under normal use, electrical appliances should not produce any electrical shock by having loose protruding wires and so on.