All child restraints have an expiration date. Seats can expire 6 years from the date of manufacture, although this can vary by manufacturer. Expiration dates are highly debated, with proponents and manufacturers claiming that older car seats can degrade over time to be less effective and that changing laws and regulations necessitate an expiration date. Opponents argue that it is simply for their legal protection and to sell more car seats, and point out that manufacturers have noted that the plastics in most car seats long outlast the expiration date. As ageing is due to temperature swings and UV-light, a seat ages faster in a car than in a cool, dark cellar.