Do you have a chainlink gate that you want to keep little ones from exiting, but don't want to totally lock it or don't want to mess with a pad lock because it takes too long to open? My solution was to get a little carabiner type thing and put it through the hole. The little kids don't know how to undo it but the bigger kids can get out if they want. Also, it is much faster to unhook than trying to remember a code or mess with a key. Of course this is not super safe, but what 4 foot fence is anyway?