Pros:
Excellent dampening effect and volume reduction compared with mutes made of other materials such as rubber. High quality item that is well finished and won't spoil the bridge or strings.
Cons:
As a metal item it has a small weight to it which becomes noticeable after extended practice. Not really a negative, just something to be aware of.
Other:
An excellent quality item that is good value for money as you'll never need another. Professional service and timely dispatch by the company.