Universal backstrap -- you can get it elsewhere if you even need it
Crutchfield Customer Review (What's this?)
I purchased these based on recommendation from my advisor, but ended up not using them. If you need them, having them conveniently packaged with your order is great, but this is basically plumbing hanger tape that can be purchased in much larger quantity for a much cheaper price from your local hardware store if you end up needing it. I'm not sure I'd recommend these for those reasons (easily obtained elsewhere for cheaper, in the event you need it).
Pros: Convenient when packaged in with your order. Strong strapping.
Cons: Easily obtainable elsewhere (any big box hardware store) for much cheaper, if you even need it.