It's not rocket science exactly

I was at the store last week and this oxiclean laundry ball caught my eye. I debated on buying it, but in the end I decided to give it a try. I was thinking that not having to put detergent in my washing machine would be just one more step I could miss. It consists of a hard ball of detergent that you put inside a soft ball that has holes in it and releases the detergent into the laundry at the rate of just enough to clean a load. All together the ball does 25 loads. Another plus is you leave it in the bottom of your washer all the time. So far so good. It really seems to be working and my clothes have come out nice and clean. Hubby got back from school last night and I decided to share my enthusiasm for the laundry ball with him. After explaining what it does and how it's supposed to work, he looks at the ball, puzzled, and says "how does the ball know how much detergent it's supposed to release?" I'm thinking "who cares," but I say "how am I supposed to know, I didn't invent the thing, I'm just using it in my washer." I told him if he really has a burning desire to know the answer to this, he can call 1-800-oxiclean and ask them. What do I look like, a rocket scientist?