I bought 10 of these and have used 5 so far.
Just the change of tailpiece made a significant improvement to the sound of two of the violins. The treble was reduced and the warmth increased. The sound of the other three violins were not noticeably affected for good or ill.
The screw threads are very fine so the tuning can be set very accurately.
The E adjuster has a range of about 6 semi tones.
The A adjuster has a range of about 9 semi tones.
The D adjuster has a range of about 10 semi tones.
The G adjuster has a range of about an octave.
So plenty of adjustment available on all strings.
The levers that move to adjust the pitch are very well made; deep and wide, with a groove where the screw contacts to keep the screw and lever centred.
The levers pivot around a substantial wire fulcrum. The holes in the lever are drilled to a close tolerance and the levers do not waggle and drift laterally but stay aligned as they should.
There is no tail cord included which is clearly stated on the product page, so don't forget to order one if needed.
The screw threads do not come pre lubricated. In this condition they do not move smoothly in normal usage with the strings attached. If left this way pre mature wear will take place.
Light spray lubricants evaporate, heavy oils and greases eventually become thick and sticky.
I use copper based grease with micro fine copper particles which retain smooth lubrication over extended periods of time.
Dip the end of the screw into the copper grease and screw down the full length of the threads to spread the grease. A smear of grease will be left where the screw contacts the lever providing lubrication at the point of contact.
In conclusion: an excellent product but don't forget to add lubrication.