We have tried: We tested the balls in both the washing machine and the dryer.
Use in the washing machine: they helped separate the laundry from each other - the laundry did not get tangled, after washing the laundry was not "stuck" to the drum of the washing machine (spin speed was 800).
Using in the dryer: the balls aerated the laundry and textiles in the dryer, which made the drying process faster and shorter. The laundry was also less wrinkled.
Washing and drying laundry is more efficient . They are designed for repeated use.