Multi Bolt - BLACK, Best Heavy Duty Baby (Infant, Toddler) Safety Window Locks, Fits Double Hung, Sash, & Sliding Windows With Easy Install - Child Proof Your Home

I looked at so many options for our windows-this is best I found! My son is 4 and can reach any kind of device that is supposed to keep the window from opening so I had to have something that locked. These locks make so much sense because he cannot "outsmart" it-you must have the key, period. I found others that locked but they had separate keys for EACH lock, I have 15 windows so that would not be an option! These all use the same key and work exactly as they are supposed to, plus are super easy to install-We put in 4 of them in under 10 minutes. Thanks for making a practical and useful way to keep my child safe.