I'm not sure if the rubber band was supposed to be with the package but I can't see it.
quality is good. Be aware the tail light is not powered by the battery : it's an old shitty tail light with two AA batteries, you need to remove the light (not easily) and change the batteries everytime they're empty, that is every 5 hours or so if you use rechargeable batteries. I would say it's stupid to put such a light when you've got this big battery to give power.