With proper storage, normal shelf life is seven years. The quality of a Carlisle belt is not considered to change significantly within seven years when stored properly under normal conditions. Normal conditions can be defined as temperature below 85°F and relative humidity of 70% or less with no exposure to direct sunlight. Beyond seven years, assuming normal storage, a decrease in service life of approximately 10% per year can be expected. For belts not stored under “normal” conditions, the actual reduction in shelf life is difficult to measure due to lack of precise data and number of variables involved. When belts are stored under abnormal conditions, conservatism is recommended in estimating shelf life.
All Carlisle belts have a 4 digit number to identify when they were manufactured. The first 2 numbers indicate the week the belt was produced and the last 2 numbers identify the year. For example, 2716 means the belt was manufactured during the 27th week of 2016.