The recent technological improvements in lower limb prosthetics have been impressive. But only a small part of these improvements have been transferred to pediatric prosthetics. Most pediatric knees do not offer any walking speed adaptation which leads to gait deviations and not being able to catch up with other children. That is why we have developed the mKnee series: a pediatric knee with a polycentric design combined with the hydraulic swing phase control. This knee offers children from the age of 1 ½ onwards a stable and natural gait. The swing phase control greatly supports children in their activities and prevents the development of unwanted gait deviations. The mKnee comes in three sizes, a pre-school version, a school-age version and a youth/adolescents version (mKnee Explore, Play and Perform (TBR)). For each version, the weight, robustness, and control are adapted to the needs of the children in that age. With the mKnee series, children are not restricted in their activities.