We have a Houdini baby and our upstairs windows don't have locks. This then became a big problem when our child got out of her cot and started playing with her window. We ordered this lock as the ones designed for baby proofing had mixed reviews, and we have found that if there is any possibility a child can find a weakness in a product ours will find it I am so pleased that I made that choice. It took my husband 5 minutes to fit the lock to the frame and that included drilling the pilot holes, he was very impressed with how easy it was to fit and it gives us piece of mind that our child wont be falling from the window. I would highly recommend this lock as it is a sturdy well built item that is made of metal (it is quite heavy for how small it is), it looks like it is a cast piece and there are no plastic parts. After seeing the product we are considering buying some for the downstairs windows for extra security, it is an excellent product and I would highly recommend for baby proofing or extra security.