I don't know if my babylock crescendo is plastic inside but it sure is heavy. If it's plastic, it must have rocks inside. I really like the pivot feature so haven't used the knee lift. The dual feed attachment is nice as i always have had trouble getting walking feet on my machines. So far, i am not impressed with the sensor pen and laser light. If I was doing it over again, i would rather have the Aria which wasn't out yet when i bought the crescendo.