Ordered a couple of these, worked just fine. They do have a stop, but it is not a set screw type stop, but a fixed roll pin (can be filed or driven to adjust height), and they are see through. They are coming from Asia, so allow plenty of time for delivery (10 days, for me...).

http://cgi.ebay.com/ONE-PIECE-25-4MM-SEE-THROUGH-RIFLE-SCOPE-MOUNT-h188_W0QQitemZ330316644115QQihZ014QQcategoryZ7307Q QcmdZViewItemQQ_trksidZp1742.m153.l1262?_trksid=p1 742.m153.l1262