Really cool!! Really small too!!!
http://www.littlemachineshop.com/pro...ory=1963256900
Here is a link to little machine shop, I have that same mill. This is a bolt on spindle lock. I originally purchased a quick change tool ER 40 or something like that size for the r8 spindle. I eventually changed and bought all r8 collets off eBay and now just use a dewalt impact driver to change r8 collets. I can change collets in about ten seconds. Just put a pin in the spindle lock and attach impact wrench to draw bar. Quick simple and effective. Plus it puts the tool closer to spindle increasing mill capacity and rigidity. It took me about an evening of tearing down and cleaning up the ways. For me it has been a perfect little mill.