N.Y.C. Admin. Code § 27-2104

§ 27-2104 Posting of serial number and sign regarding rent stabilized dwelling units.

a. An identification sign containing the dwelling serial number assigned by the department for the purpose of identifying the registered multiple dwelling and the owner, managing agent, and agent designated by the owner for the collection of rental payments if different from the managing agent, shall be posted in every multiple dwelling in the manner and location prescribed by the department.