Ohio Concrete’s Safety Truck Decals These brightly colored truck decals warn customers and employees of hazards associated with confined space and fresh concrete. The decals measure 8.5 x 11″ and they are durable and self adhesive making them easy to apply. Choose from the following: Caution Confined Space – The most common confined space in your business is the mixer drum on your trucks. This decal boldly identifies this area as a confined space. Caution Fresh Concrete – This decal warns of the potential dangers of fresh concrete. Including burns and eye injuries. Every ready mix truck should display this sticker in a highly visible area. Danger Confined Space Permit – OSHA demands that all confined spaces which require a permit to be obtained before entry be visibly marked. This decal informs employees, customers, contractors, etc., about the importance of confined space permits.