I did not check my time for assembly as I was doing things in between but it was fairly simple. I use an older bike and had no issue installing a 7-speed cassette with a 4-mm spacer. Lastly the controls on the headphones work well and seem to ge built solid. Upper doesnt breathe well enough to wear sockless all day. The sound quality is not perfect but it is excellent for earbuds at this price point. So comfortable and absolutely perfect as slippers, especially if you are like me and go out to the bins or garage in slippers. An overall good YA read with very likeable characters and a story to get lost in! I needed an alternative to finish drying my professional work clothes without hanging them over the door or on door knobs. The slippers are NOT for a wide foot. EDITADO: Después de un mes de uso dejo de funcionar.