Aluminum signs are quite durable for playground signage. The 40 mil version has an outdoor life of at least 7 years, while the 63 mil thick version easily lasts for 10 years. The 40 mil signs come with steel stakes for some designs and offer an outdoor life of 10 years. The reflective Designer Playground Signs are very thick (80 mil) and durable too. If greater durability is required, go for Diamond Grade reflectivity (12+ years), High Intensity (10+ years), or Engineer Grade reflective signs (7 to 10 years). Laminated plastic labels carry an outdoor warranty of 5 years.