Bass Guitar made by American Instrument company Rickenbacker in 1961, serving a period of twenty years before being discontinued in 1981 in favour of the updated 4003 version. Despite not selling as well as the Rickenbacker 330, the 4001 has risen to arguably become Rickenbacker's most popular model in its history while also being one of the standard bass choices in progressive and classic rock as well as important blips in the post-punk and metal scene.
Its key visual traits are its round and curvy body design with a long asymmetrical cutaway on one side, its iconic "crested-wave" headstock, its differently sized pickups with a large bridge pickup encased in a chromed plate, and its unusual bridge.
Despite being an updated version, the 4003 model features little to no differences to the untrained eye making it almost identical to the first release of the bass.
FLCL's Haruhara Haruko is the most well known character in Japanese media who uses a 4001, often used as a Weapon, a Baseball Bat, specifically.