A 10 years old boy comes to the clinic presenting with a distal step molar relation in the mixed dentitional stage. He would most probably need which of the following appliances?

Nance holding arch is a space maintainer. The boy in this case is having class III tendency. So a myofunctional appliance is required to correct this. Oral screen is used to intercept habits, to perform muscles exercises and to correct mild anterior proclination.