Vehicles which do not exceed 25mph are categorized as 'slow moving.' By law, they are required to bear a sign warning others of their lack of speed (check your local laws for specific information). This sign is called a Slow Moving Vehicle Emblem and must be mounted on the rear of any vehicle unable to achieve the same high speeds utilized by cars and other vehicles that may use the same roadways. The purpose is to warn approaching vehicles that they will need to slow down or prepare to pass the slow moving vehicle with safety and caution in mind.
The Slow Moving Vehicle Emblem has been used for 50 years with success and is universally recognized throughout the world. Although some countries have adapted it to have a different appearance, the purpose and meaning behind it are all the same. In the United States, this emblem looks like an equilateral triangle with the three tips cut off. In the center is a yellowish-orange triangle with a red border on all three sides that is reflective. The center color of the triangle is designed for daylight visibility and the reflective edges are designed for visibility in darkness. Some color variations are present as are variations in the power of the reflective section, but overall the general appearance is very much the same. Size requirements vary by state but this emblem should be large enough to be seen from a distance to allow others on the road to recognize it and have time to react. The ideal distance from which this emblem should be visible is considered to be 600 feet.
Placement of the Slow Moving Vehicle Emblem is also important. It needs to be placed on the rear of the vehicle as near to center mass as possible. It also needs to be at least two feet off the ground but no higher up than six feet (again, verify all laws for your local area as some variations are possible). It needs to be affixed to a flat surface so it is visible from directly behind, as that is the direction from which another road sharer would approach.
Watch out for the State regs!
As we said, be aware that these laws change from state to state in regards to requirements for and use of the slo-mo vehicle emblem. For instance in Oregon the state requires that "Golf carts or similar vehicles when operated by a person with a disability..." must have the familiar orange triangle, while many other states have no issue with golf carts. Meanwhile, just over the line in California, while golf carts are not mentioned specifically but the size and location of the emblem are very specific, stating that : "mounted on the rear of the vehicle, base down, and at a height of not less than three nor more than five feet from ground to base. Such emblem shall consist of a truncated equilateral triangle having a minimum height of 14 inches with a red reflective border not less than 1 3/4 inches in width and a fluorescent orange center."
So yeah, keep that state requirement met.
This sign is important not only because it is required by law, but also because it is in the best interests of those who use roadways on which other vehicles operate. You need to give yourself the best possible chance of being seen so drivers will be able to avoid you. Distracted drivers are extremely common these days and your life is at risk every time you share the road, so give yourself all the advantages you can; wear your Slow Moving Vehicle Emblem big and bright so you will survive your work in both day and night.