It is a common occurrence whereby the OK or SOS under display has been mistaken for the opposite! (This seems impossible but if a competing vehicle arriving at the scene does not have time to note the displayed board then after passing they will actually note the opposite display in the rear view mirror!) In the heat of the moment mistakes can happen.The all new and unique Vision OK/SOS board can only display OK or SOS at any one time. Using a simple folding technique coupled with the strong but failsafe hook and eye fastening method, the Vision board can be changed over in less than two seconds. Contains additional hook and eye fasteners to allow choice of stowage.A4 size to comply with MSA regulations.