Aluminum arm. Good fit of the arm on the mirror without leaving gaps. Plastic construction of the case with anti-slip stickers on the grips and ball clamp to secure it to the arm (requires a man's tightening!). Switch that locks the grip to the size of the phone providing additional stability. Mechanism with a spring, I put a little WD40 inside before installation for lubrication and slight waterproofing of the mechanism. ATTENTION!!! Install it and use it only if you know what you are doing to avoid surprises, otherwise take it to a professional or someone who knows what they are doing with their hands. Installed on a new Chinese Daytona 125, which is known for the rumbling and the resonance-shaking that its engine makes throughout the bike. The phone hasn't made a sound. It also has a good price, purchased for 7.10 Euros!

GREAT CAUTION
IN POTHOLES IT LOOSENS AND THERE IS NO WAY THE PHONE WILL STAY IN PLACE. My phone broke on the first day because it unlocked while in motion and my €10 cost me the phone. I regret buying it. Get any other one except this. I bought it because it's a brand and I paid a lot for it.
It doesn't fit properly in the mirror and the support kept falling off because the ball was slipping. 1 day after my phone broke, I threw it in the trash. The worst thing that has ever happened to me.

With one move it goes in and out. Delivery works perfectly for two months. Before I put it on, I oiled the springs just in case it gets stuck when opening and closing.