I've used black zip ties since learning about them on this (I think) forum shortly after I bought my bike and discovered that one of the fastening prongs on my right battery cover had been snapped off. (The cover was hanging on by nothing but friction and slight resistance from the remaining two prongs.) I learned the hard way that Bob's' bungie does not fit the R65. Luckily, it wasn't a lot of $$, so I wasn't upset. (I believe that the parts folks at Bob's (except possibly Bucky, the Parts Manager) really don't know this little piece of arcane R65 information.)
Finding black zips can be a hassle, for they aren't grocery-store items. I've found the best tactic is to check every cord-bearing appliance, electronic, or yard-tool item I buy. (Some of the ties accompanying the latter are quite long, enabling custom-fitting.)
FWIW, I've heard that strips of black pantie hose make a good bungie for battery covers. I don't have easy access to those, so I'll have to stick with zip ties.
<< hardly noticable against the black side covers! >>
If tucked inside the louvers after being twisted, they are completely invisible. (Just remember to inform another person who has reason to remove the covers -- like a service department technician.)