1)8.0MM is for luthier new designed violin NEW VIOLIN Making 

If you are repairer or you have your old violins need to replaced the traditional pegs to geared pegs please be aware to ask us before you buying , because old violins the wood fiber in the neck already extended by your exisited pegs , please check the rod size before buying if you are repair or replaced your violins old pegs !!

2)8.7mm is for replacment of your violin in hand if you want to replace the traditional wood violin pegs you can chose the 8.7mm diamter of the geared pegs 

This is for luthier new designed violin NEW VIOLIN Making If you are repairer or you have your old violins need to replaced the traditional pegs to geared pegs please be aware to ask us before you buying , because old violins the wood fiber in the neck already extended by your exisited pegs , please check the rod size before buying if you are repair or replaced your violins old pegs !!

The new designed finetune geared pegs, a "non-slip" peg solution for your violin.
For proper sizing, check out our infographic. NAOMI finetune geared pegs are measured by diameter at ring.

Available in different size options:

8.0 mm & 8.7mm Violin (for 4/4 - 3/4 size violin)

Finetune Peg Set includes 4 pegs
Made from composite and light alloy material, maintaining the traditional hardwood appearance demanded by professional musicians. Installed by pressing into place without glue. Peg shaft stays in place, and tuning is done by turning peg head. There is no peg/pegbox friction, and peg is not affected by climate and humidity changes.

Only the button and the geared middle section of the shaft on which the string is wound, moves. The Fine Tune pegs have an internal gearing ratio of 8:1 for precise tuning.

We recommend installation by a professional. Before placing your order, we recommend looking at the sizing chart for proper sizing.

Package included: 4PCS-Violin Geared Pegs A SET