Hockey was a subtheme of Sports introduced in 2003. With three exceptions, no actual Minifigures were used in it, instead, hockey players are built out of TECHNIC pieces. The sets were mainly based upon different unique players, with the exceptions of the Minifigures-included sets. Some 2004 sets were McDonald's promotions. Some Hockey sets are very sought after for TECHNIC builders for the spring piece which is useful for return-to-center steering mechanisms.