is often used instead of a swiveling flag. Today, in all scales, traction magnets are sometimes used to provide downforce to help hold the car to the track at higher speeds, though some enthusiasts believe magnet-free racing provides greater challenge and enjoyment and allows the back of the car to slide or "drift" outward for visual realism. Common slot car scales There are three common slotcar scales (sizes): 1:24 scale, 1:32 scale, and so-called HO size (1:87 to 1:64 scale). These are also commonly written as 1/24, 1/32, 1/87 and 1/64. Usual pronunciation is "one twenty-fourth", "one thirty-second", and so on, but sometimes "one to twenty-four", "one to thirty-two". 1:24 scale cars are built so that one unit of length (such as an inch or millimetre) on the model equals 24 units on the actual car. Thus, a model of a Jaguar XK-E (185 inches or 4.7 m overall length) would be long in 1:24 scale. 1:24 cars require a course so large as to be impractical for many home enthusiasts, so most serious 1:24 racing is done at commercial or club tracks. 1:32 scale cars are smaller and more suited to home-sized race courses, but they are also widely raced on commercial tracks, in hobby shops or in clubs. This scale is the most popular in Europe, and is equivalent to the old #1 gauge (or "standard size") of toy trains. A Jaguar XK-E would be about in 1:32 scale. HO-sized cars vary in scale. Because they were marketed as model railroad accessories, the original small slot cars of the early 1960s very roughly approximated either American and European HO scale (1:87) or British OO scale (1:76). As racing in this size evolved, the cars were enlarged to take more powerful motors, and today they are often 1:64 or larger in scale; but they still run on track of approximately the same width, and are generically referred to as HO slot cars. They are usually not accurate scale models, since the proportions of the tiny bodies must often be stretched to accommodate a standard motor and mechanism. The E-Jaguar scales out to long in 1:87 and in 1:64). Although there is HO racing on commercial and shop-tracks, probably most HO racing occurs on home racetracks. In addition to the major scales, slot cars have been commercially produced in 1:48 scale and 1:43 scale, corresponding to O gauge model trains.