Changing a standard public restroom to a pay toilet is as easy as installing a lock. Companies such as Monarch Coin & Security offer universal coin locks that can be installed on standard restroom doors. The locks are $295 each, which includes 50 tokens for token-operated models. The company sells additional tokens for $22 per hundred tokens. Monarch advises potential lock-purchasers to measure the thickness of the restroom door and note whether the closed door is flush with the jamb of the restroom or individual stall so they can choose the right lock for their pay toilet.