Here are four Metz related wrenches from my collection: (from left to right).
1. PAT'D OCT. 18, 1898
2. PAT MAY 11, 1897 - OCT. 18, 1898 - FEB 20, 1900
3. Same patent dates as No. 2 and also marked with a three oval logo
4.Same patent dates as No. 2 but it doesn't have the square stud shown on Metz's Oct 18, 1898 patent.
all three patent dates are on DATAMP
Metz's Oct 18, 1898
http://www.datamp.org/patents/displayPatent.php?pn=D29520&id=25431 (http://www.datamp.org/patents/displayPatent.php?pn=D29520&id=25431)
Schrader's May 11, 1897
http://www.datamp.org/patents/displayPatent.php?number=582,238&type= (http://www.datamp.org/patents/displayPatent.php?number=582,238&type=)
Schrader's Feb 20, 1900
http://www.datamp.org/patents/displayPatent.php?number=644,033&type= (http://www.datamp.org/patents/displayPatent.php?number=644,033&type=)
(http://i222.photobucket.com/albums/dd3/buswrench/message-board/metz-patented-bike-wrenches.jpg)