BMX bikes for freestyle riding are known as "freeride" or "mountain biking". These bikes are designed to withstand heavy use in off-road environments, so they usually have thicker frames and stronger brakes than ordinary road bikes. They also tend to be larger than average sport bikes, with longer wheelbases and more tire contact with the ground. Freeride bikes are generally based on the standard mountain bike design, but with several key differences: fewer gears, smaller wheels, and shorter chainstays for better maneuverability. There are two main types of freeride bikes: those that are intended to be ridden down steep hills and hurtled through gaps in walls of mud or ice, and those that are used for exploring single-track trails hidden away in forests. The former type is often called a "grommet", after the metal inserts which hold the tires in place on such bikes. The term "Haro" is short for "Haro Bikes". It was originally an Italian brand that produced quality bicycles from the late 1950s until 2004. However, due to financial difficulties, Haro was forced to shut down its factory and now only imports its products from China and Taiwan.