The sand barrels come in a number of different sizes so you can find the ones that will work the best for your particular situation. You will notice that the colors for the sand barrels tend to be yellow with a black lid or black stripes. The reason for this is simple. Those colors are the ones that most people associate with caution and danger on the roads. The lids of the barrels go on snugly once you’ve filled them with sand. Keep in mind that when the barrels are full of sand, they are extremely heavy and will be difficult to move.