The maximum price a seller is allowed to charge for a product or service. Price ceilings are usually set by law and limit the seller pricing system to ensure fair and reasonable business practices. Price ceilings are usually set for essential expenses; for example, some areas have "rent ceilings" to protect renters from climbing rent prices. Price ceilings are regulations designed to protect low income individuals from not being able to afford important resources. However, many economists question their effectiveness for several reasons. For example, price ceilings will have no effect if the equilibrium price of the good is below the ceiling. If the ceiling is set below the equilibrium level, however, then there is a deadweight loss created. Other problems come in the form of black markets, search time, and fees, which are added but not directly associated with the sale - for example a high charge for fittings could be added to a maxed out rental cost.