I bought this because someone snapped my mirror off and left it by my bike. These are worthless. The slot is too small for my mirror threads, the clamp has no threads in the slot and if I tap in threads I believe it will crack. Now I have 2 clamps that are sitting on my shelf.
The mirror case is made of plastic and doesn't hold the mirror well enough when riding. The mirror is shaking a lot and I can barely see anything behind me. On left side I still have my original metal case mirror installed so I can compare, the original one is nice and steady, while this one is shaking and makes it tough to see anything. It's okay for the price, but if you want good, reliable mirrors, look up something else. They're also smaller than the original ones.
Took a bit of modification to make it work with factory-installed grip heaters had to drill out the aluminum clamp housing from Bikemaster. Not their fault though- I bought the mirrors knowing it would take some work. Taking time to carefully tighten everything ensured no damage. Great field of view. No vibrations (this is on a BMW boxer)! Small negative: when pivoted in to split lanes, the mirrors will contact my knuckle guards of my riding gloves. But for the price, I'm more than happy.