A pro-style offense in American football is any offensive scheme that resembles those predominantly used at the professional level of play in the National Football League (NFL), in contrast to those typically used at the collegiate or high school level. Pro-style offenses are fairly common at top-quality colleges but much less used at the high school level. The term should not be confused with a pro set, which is a specific formation that is used by some offenses at the professional level. Generally, pro-style offenses are more complex than typical college or high school offenses. They are balanced, requiring offensive lines that are adept at both pass and run blocking, quarterbacks (QBs) with good decision-making abilities, and running backs (RBs) who are capable of running between the tackles. Offenses that fall under the pro-style category include the West Coast offense, the Air Coryell offense, and the Erhardt-Perkins offensive system. Often, pro style offenses use certain formations much more commonly than the air raid, run and shoot, flexbone, spread, pistol, or option offenses. Pro-style offenses typically use the fullback (FB) and TEs much more commonly than offenses used at the collegiate or high school levels. Part of the complexity of the offense is that teams at the professional level often employ multiple formations and are willing to use them at any point during an actual game. One example might be that a team uses a Strong I formation run (FB lined up where the TE is located on the line of scrimmage) on 1st Down followed up by a running play out of the Ace formation on second down before attempting a pass on 3rd down out of a two-WR shotgun formation. Another aspect of the complexity is that the running game is primarily built on zone blocking or involves a power run scheme. Both of these require an offensive line that is very athletic, one play they could be trying to zone block a Linebacker, and the following one could be power blocking a defensive line. Most of the blocking schemes involve a series of rules, or a system in which they operate their blocks. The passing game as a result often employs play-action, often with the QB dropping back from under center, as a means of passing the ball while building on the running game. Coaches who make the transition from the NFL to the NCAA as head coaches