brown faux suede (vegan) wide collar with silver eyelets and corset lacing. 
can be laced in the front or the back, or off to the side. 
the opening IS the lacing, so you will have to unlace it and relace it to wear it.  
you can also easily replace the brown cord with another ribbon or cord or something if you don't like what it comes with :) 

MEASUREMENTS: about 11.5" around fully closed. 
so good for necks over 11"  (but probably under 15" or so, unless you buy yourself a longer ribbon) 
That's fairly slender.

 Lots of other necklaces, including this design in other colors, in my ebay store.