Some washers came with these. I have and still use a washer from the eighties that has one of these. It's called a "mini" basket and was used for washing just a small item or two. The washer you use these baskets in has to have an agitator built to accept it and a cycle setting for the "mini" wash. I don't think it is more gentle, but it obviously uses less water. You still might be able to purchase this kind of washer with the mini basket, but I doubt that's the route you want to go.
Give us this day our daily bacon.