The most complained about feature of these locks, in general, is that they do not fit or do not work on the particular window they were intended for. This is understandable because of the vast number of window types and track sizes that are in use in homes. Some people said these were too big, while others said they were too small. A few comments said that several of the models came off easily and were easy for their kids to remove or open. It is important that the child not be shown how these locks operate because they will then be able to open them themselves. As far as the sizing issue, the sizes and accommodations of the locks are given in the manufacturer’s details of each type. We suggest that you look at those closely before ordering any of these locks. You will save time, aggravation, and money by ensuring that the ones you order are the correct size for the window you want to lock.