For any given substance, the heat capacity of a body is directly proportional to the amount of substance it contains (measured in terms of mass or moles or volume). Doubling the amount of substance in a body doubles its heat capacity, etc.
Conventional soft contacts can last up to a year; conventional rigid gas permeable (RGP) contact lenses can last even longer. Frequent or planned replacement contact lenses last one to several months. Disposable contacts last from one day (daily wear) to up to two weeks (extended wear).
EXTENDED WEAR. Extended wear contacts lenses are designed for overnight wear, and can be worn for up to 30 days. These lenses are made to allow more oxygen to the eye. The recommended length of wear depends of the type of contact lens your doctor feels will work best for you, along with your eye health. We often recommend you remove your contact lenses at least one night a week to rest your eyes.