No other detergent required but I do add oxy clean to my whites and lights, just like I did when I used detergent. I also add baking soda to loads with fitness wear. I instruct my teen to add baking soda to every load, too. (which I also did with regular detergent.)
They generate their own hydrogen peroxide like reaction in the water, they absorb odors and stains. They last for 1,000 loads.
I first heard about them from SamRose, for those of you who remember her. I know her in person and she is not only extremely frugal, she is someone who WILL get her money back if a product doesn't work.
So, when I found out she was still loving hers a year after purchase, I bought some.
I had formerly been a longtime user of Charlie's Soap.. Still like that as a detergent but I love my laundry balls.
I think I've had mine almost a year. Not sure. Maybe longer.