Complex sentence: Today, original bell bottom pants and flares from the 1960s, 1970s and 1980s are collectible vintage clothing items worn by people attending retro-themed disco parties and by members retro revival bands.
Split into simpler sentences: Today, original bell bottom pants and flares from the 1960's, 1970's and 1980's are collectible vintage clothing. Items that are worn by people attending retro-themed disco parties and by members retro revival bands.