Review on Child Safety Window Locks - Kamtop Window Restrictor Locks With Security Cable & Keys For Baby, Casement & Door Safety - Anti-Theft Window Guards (4 Packs) by Francisco Garcia

I used these as extra door locks as I have a 5 year old that likes to prove his independence by sneaking out of doors. The screws were small enough to drill into the door without going through and have held up well. I probably should have used anchors on the other side, but what's done is done. Lesson learned. They very easy to install. Very self explanatory. The keys they come with are small enough to keep in your pocket without getting annoyed. I'll be moving in a few months to a home with slider windows so I'll probably buy some more for those.