The National Association of Theater Owners has asked studios to limit movie trailers to two minutes — chopping 30 seconds from the current norm.

NATO announced the voluntary guidelines Monday. The new rules won’t go into effect until Oct. 1.

The new guidelines also state that studios will not be allowed to show a trailer for a movie more than five months ahead of its release. However, distributors will be allowed two exemptions a year on both trailer length and marketing lead time.

NATO said that the guidelines were initially adopted in April and have been revised following discussions with executives of the seven largest distributors and other distribution executives.

“These guidelines will evolve in response to technological innovations, marketing and advertising trends, competition in the marketplace, and consumer demands,” NATO added. “The guidelines are completely voluntary and will be implemented through individual exhibition company policies, which may vary.”