These small airtight bags are of poor quality. They are much too thin, so thin they almost tear when opened because of the resistance of the closure. They are as fine as cellophane! I bought these bags to hold the small screws and other very small objects "precious". I did not want to take the risk of misplacing therefore I will not use these bags and try to find some good quality this time. The problem is the same for models 40 and 60 * 60 * 90. I'm really disappointed!