I've heard alot of negative input on these types of vises.. Here are a few fairly nice ones you should consider purchasing..I plan on ordering the 6'' CNC super vise here soon myself!

http://cgi.ebay.com/6-CNC-SUPER-VISE...item4ceba04ab6
http://cgi.ebay.com/6-ANG-LOCK-VISE-...item4835c4c1d9
http://cgi.ebay.com/4-ANG-LOCK-VISE-...item4833332a1f