OSHA Danger Safety Sign:Indicate the hazards of crystalline silica, and prevent unauthorized access in those areas.Plastic Manufactured with 50% Post-Consumer Recycled plastic and is recyclable – code 2. .055" thick polyethylene, matte surface print. Impact resistant with slight flexibility. Rounded corners and 3/16" mounting holes on most sizes, will be adjusted for larger sizes. Service temperature range: -90°F to 168°F.