Straddles and spreads were illustrated using calls, but comparable strategies constructed using puts. Straddles and spreads may be expanded; Problem 17 illustrates the strip, in which the investor buys one call and two puts, and the strap, in which the investor buys two calls and one put. Problem 18 illustrates the butterfly spread, in which the investor buys (or sells) one of each of two options with different strike prices and sells (buys) two options with a strike price between the two options that were purchased. Additional option strategies are illustrated in Problem 19