It is the most commonly used rapid maxillary expansion screw in patients that are in the mixed or early permanentdentition. It was designed by Briederman and it is totally made of stainless steel and does not have any acrylic, soit is very hygienic.The appliance is constituted by:1. Four bands, 2 on the first premolars and 2 on the first permanent molars.2. An expansion screw placed on the midline of the palate separated 3 mm from the palatal mucosa. Thisseparation is important, because when the maxilla is separated, the palatal vault descends Y9.34)3. It also has two palatal support arches soldered to the band providing more rigidity to the appliance. In casethe premolars have not erupted yet, the extension arms are contoured up to the first primary molar.