Functions of Dynamic Seating: Swiveling armrests: The armrest can swivel by 45°; the armrest bracket can swivel by 180°; the adjustable height range of the armrests is 6 CM. Backrest: L380mmxW360mm. FDA for Portable Dental Unit: 510(K) Number: K111907, Regulation Number: 872.6640, Product Code: EIA.