 One popular joke from the film features Nigel Tufnel displaying the band's amplifiers which are calibrated up to 11, instead of up to 10, allowing them to go ""one" louder".As a consequence of this, manufacturers began making amplifiers with knobs that went up to 11, or even higher, with Eddie Van Halen reputedly being the first to purchase one.Marshall, the company that provided amplifiers for the film that the custom marked knobs were applied to, now sells amplifiers such as its JCM900 (first sold in 1990) whose knobs are marked from 0 to 20.