A convertible is a car with a roof that can be removed or folded down, but is often seen without a roof. A convertible usually has two doors, but convertibles with four doors can also be found. Some examples are Mazda MX-5, BMW Z4, Ferrari 458 Spyder, Mercedes-Benz SLK Class, etc. A convertible is a type of automobile of various automobile body styles that can convert from open-air (top-down or topless) mode to a provisionally enclosed (roofed or top-up) mode. Convertibles evolved from the earlier Phaeton, a similar vehicle without glass side windows that may or may not have had removable panels of fabric or other material instead to protect passengers from rain and cold, etc. A semi-convertible or cabrio coach is similar to a convertible and also has a retractable or removable top, but has fully framed windows on its side doors as opposed to a convertible's roll-down frameless windows that provide an even more open car driving experience.