Trying to find more of these safety locks

We had our windows installed about 20 years ago. When we had them done, the installer gave us a bunch of extra of these safety locks because he said they can break easily if not pushed in before opening the window. Well, over 20 years and several kids, we have gone thru all of the replacements and I need to get some more. I started off looking in Home Depot and Lowe's but they were no help. Then I tried a couple of specialty shops in my area and neither of them has gotten back to me about whether they can get them or not. Any help would be appreciated. Thank you.