 PowerScope is delivered as a one-size-fits-all appliance pre-assembled with attachment nuts for quick and easy chairside application. The appliance is a wire-to-wire installation with attachments placed mesial to the first molar in the maxillary arch and distal to the canine of the mandibular arch. Although there are a few case reports in the literature showing the treatment effects and clinical application of PowerScope, there is not a single study mentioning the effects of PowerScope appliance, which has a different status from other fixed functional appliances due to its special attachment. The purpose of this clinical study was to evaluate the skeletal and dental changes produced by the PowerScope and compare these effects with one of the most commonly used fixed functional appliance the Forsus Fatigue Resistant Device FRD. 