Where there is no covenant to the contrary, the lessee can put the premises to any legal use subject only to the principle of waste. However, it is common to have a restriction on user clause. This can be on the type of business, trade allowed, or hours of operation. Hours of operation may include a covenant to stay open for certain hours. Further, the tenant may covenant not to conduct a similar trade within a certain radius of the subject premises. All such restrictions must be clear and unambiguous otherwise they will fail for uncertainty.