Standard Models: Produced/Originally Sold in ~Late 2013 to ~Late 2016: White Sticker on the Right Side Diagonal Frame Member, Near the Motor & Rear WheelStandard Moldels - Produced/Originally Sold in Late 2016 to Current : White Sticker on the Back of the Chair on a Horizontal Frame Member, Near the Folding BarDeluxe Models:  Produced/Originally Sold in ~Mid 2015 to ~Late 2016White Sticker on the Right Side Diagonal Frame Member, Near the Motor & Rear WheelDeluxe Models: Produced/Originally Sold in ~2017 to CurrentWhite Sticker on the Back of the Chair on a Horizontal Frame Member, Near the Recline Mechanism Clamps.The Serial Number is also Etched into the underside (bottom) of the Diagonal Frame Member "Side Beam" on the Right Side.The White Stickers Display The Following Lines: Style No.:Lot No.: Mfg Date: