A fence or collar is an option strategy that establishes a trading band around a security or commodity, generally to protect profits. One form of a fence involves the sale of an out-of-the-money call option on an underlying security; all or part of the premium thus received is used to buy a protective out-of-the money put on the security. Both the call and the put have the same expiration date. The call option establishes a ceiling price for the security, while the put option establishes a floor price for it, effectively 'fencing' in the option.