DURABLE. Slider signs are made from a 60 mil (roughly 1/16") thick engraved plastic plate recessed within a solid anodized aluminum frame. SLIDING TAB. The top plate can be easily slid back and forth to signal vacancy, availability, etc. EASY TO INSTALL. Slider signs come with foam adhesive strips and stick well. SLIDING SIGNS. Use this Mail Is Here Or No Mail Sliding sign to let people know when the mail reaches.