Right now I have a few boxes of those, they are made by Winchester. Years ago they were available at Cabela's I think it was. I bought 5 boxes of 50 but back then the prices were not high like now.
They seem to work well enough on small birds like Starlings. I have never tried using them on Squirrels. Like I said above, all you need for them is a 22lr round. Nothing special needed either but some homeowners like to use CCI Stingers or Velocitors for Squirrels. Also like I said, nothing wrong with the CCI Quiet-22 ammo. Since they are going only 720fps you don't want to try anything over 50 yards with them, I prefer within 25 yards.