4 red LED bulbs along its length, each protected by a hard plastic casing. With a simple push of a button, you can turn on the LEDs to your choice of a steady or a rapid flashing mode. The flashing mode grabs attention and actually saves battery power! Even when the LEDs are off, or your battery's out, the armband consists of a highly reflective 3M Scotchlite PVC material, so you will be SEEN! hook and loop closure. 17L x 1 1/4W, of which 8 1/2L are of reflective material.