Shark VM120 Jawset 

• Shark Jaws have serrated inner and outer jaw surfaces
• These extended jaws provide an aggressive hold, they hold cylinder spigots much more safely than standard jaws  
• They are much easier to use and provide vastly better grip than traditional jaws used to turn long workpieces
• These jaws should not be used to grip the bowl on a finished surface
• The sizes indicated on the drawing are when the jaws form a perfect circle
• VM120 and VM150 chucks provide approximately 48mm of expansion beyond these specified sizes    

See the Youtube video for the features of the Vicmarc shark jaws:

https://www.youtube.com/watch?time_continue=3&v=GOsxa_Zt0ws