365 Print & Signs can design and print your custom poly bag yard signs! Poly bag signs are the lowest cost yard signs and are popular for political campaigns, residential job sites and other short term uses. These have a typical outdoor durability of 1 to 6 months in a mild climate. Unlike the Tuff board yard signs whose life span is effected most by water, with poly bag signs, the life span is effected most by wind. Conditions with the calmest wind will enjoy the longest durability.