The ARMS 41 is a clamp on flip up sight for the AR15. It is available with and without a bayonet lug.
Installation is easy. ARMS also includes a spacer in case you are not using a standard handguard. When up, the 41 has the same profile as an standard fixed front sight base. To fold it down, you push down on the angled support next to the front sight post. It uses standard AR15/M16 front sight posts, so you can insert a match or night sight.
The finish is a light grey. While I have read reports online of people having the finish wear off quickly, I had no such issues with mine. While there are reasons why ARMS is not popular, the ARMS 41 is a solid product.