Windows, usually tinted, that, when viewed from the outside, have a sort of convex bulge. They are often fitted to large vans and panel vans purely for cosmetic purposes and lend the vehicle a kind of rockin' look.

To be truly authentic, the vehicles that sport these marvels of twentieth century style should have fat tyres and big thumping stereos blaring the earlier music of artists such as Led Zeppelin, Black Sabbath, King Crimson, AC/DC, Midnight Oil, but definitely not Barbra Streisand. Fluffy dice are a welcome addition.