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).
If you prefer to design the lens yourself, use the SpecialEyes Arc Length Calculator or Prescribing Nomogram available in the Learning Center. Your trial spherical or toric contact lenses will arrive in 2 to 4 business days. Step 4: Evaluate on-eye performance of the trial contact lenses. Assess fit and visual acuity.