Diamond file set with Titanium coating. 
The small size files makes grinding and cleaning up edges of  small broken ceramics and glass shards easy.  It reaches tight corners and small cracks of porcelain and ceramics.  Important tool for detail works. (Diamond file not suitable on wood work).   
 
3 different profiles:  FLAT, ROUND, SEMI-ROUND. 
Length 140mm (5.5")
Grit #120