These armbands are made of cotton drill with a light reflective strip and have cotton bound edges.  The diameter column in the table below states the diameter arm that each armband will fit. The light reflective strips are made of 3M Scotchlite. Which can increase visibility from 30metres to 160 metres in poor light. The photographs below show the material under light and in the dark so you can see the difference in visibility. The armbands feature a clear plastic window so that a small document of your choise can be inserted in the armband. Usually used for identification purposes.