All of our aluminum “Adult Supervision Required” signs are ideal for the outdoors. 63 - 80 mil thick aluminum signs are also available in three grades of reflectivity, and each grade comes with different outdoor life. 40 mil aluminum signs also work well but are less durable than thicker counterparts. All metal signs are pre-drilled, and you can mount them on any signpost or fence on the beach. Lamination on the sign offers superior durability. Laminated signs can withstand temperatures up to 168ºF and offer great water and chemical resistance. Rust-proof aluminum signs do not bend, and they have been proven to outlast the toughest of storms.