Simple and compact lock to prevent children from falling, suitable for double-hung windows. Thank you for viewing. I made this to prevent children from going out onto the balcony without supervision, even for a moment. At least my child, at the age of 2, could unlock the lock (even the lock itself). This time, I was able to make it from resin, so I created a part that can be easily unlocked only by adults. As shown in the photo, if it's a double-hung door type, it will not open just by covering it from above. When you want to open it, just remove it and hang it on one of the doors, so you won't lose it. I think it's a part that combines convenience and safety. Also, the compatible size is as shown in the photo. If it doesn't seem to fit, please let me know the sizes of ① and ②, and I will make it to order. Please do not overestimate the safety as it is made by an amateur. Also, I cannot take any responsibility. I am also selling Numarkasten, which is popular in the Shichida method and Montessori. Please check my profile. Fall prevention Children Window Apartment Double-hung window Window Child lock Shichida method Montessori Numarkasten Kazu STEM