You are always going to have an easier time avoiding accidents when riding your bike when you have a mirror to see what’s happening behind you. RearViz has an accessory that allows riders to see what’s coming up from behind so they can take action. This is a wrist-mounted rotatable, collapsible mirror you can remove easily. RearViz is available in 2 armband lengths and has a UV resistant plastic design. It sets you back $37.50.