Pronto was the brand name used for groupsets by an alliance of three Italian component manufacturers, Ofmega , Regina and Universal. Ofmega contributed chainsets and gear sets, Regina contributed chains and freewheels and Universal completed the picture with brakes sets.
Unlike, the rather similar, French Spidel project, the components in the Pronto groupsets were not branded 'Pronto', but retained the branding of their original company. So the gears are branded 'Ofmega'.
At least 3 groupsets were marketed under the Pronto label. They were called 'Formula 1', 'Formula 2' and 'Formula 3' with the quality and prestige decreasing as the number increased - just as in motor sport. All three groupsets included the Ofmega Mistral derailleur in black. It is possible that the Ofmega Mistral included with the better groupsets had aluminium fittings at the b-pivot and p-pivot, while the cheaper groupsets included an Ofmega Mistral with these fittings made of steel.
Like Tiso, a generation later, Pronto is notable for the ugliness of its logos and the tackiness of its promotional material. Italian products are sometimes criticised for being all style and no content. Refreshingly, the Pronto offer was of surprisingly decent content, with absolutely no style whatsoever.