The Islamic finance equivalent of a conventional call option is known as an "urbun" (lit. "down payment"), the equivalent of a put option is known as a "reverse "urbun"". In each the seller has the right but not the obligation to either buy (in the case of a call or "urbun") or sell (in the case of a put or "reverse "urbun"") at a pre-determined price by some point in the future. These two Islamic options also have a different name for a "premium", (called a "down-payment") and for the "strike price" ("preset price"). The options' Islamic distinctiveness has been questioned by analysts, and its use has been criticized by conservative scholars.