We already have 3 of these lights (rear and front versions) in our household and they're great, inexpensive bike lights, so I ordered another knowing what to expect and not bothering to read the reviews for this product.
When it arrived I was surprised to find that it lacked the fixing required to attach to the bike, and just contained the belt/bag clip, as mentioned by others in their reviews. Fortunately, my under-seat bag has a spot to securely fix the light clip to, so I'm still really happy with the purchase.
Spoke to Amazon and they're going to look at, and hopefully revise, their description which I think most people will find misleading.
If you need the bike fixings, rather than just the clip, I'd recommend looking up the version that includes both the clip & bike fixings, as the light itself is great.