This is a .050 Ball Wrench (4-40 Set Screw) from Dubro.

FEATURES: Fits 4-40 set screw. The perfect tool for getting at those hard to reach places. Ball wrenches make it possible to turn socket head screws or bolts from any angle. Transparent Yellow plastic handle.

INCLUDES: One .050 Ball Wrench (4-40 Set Screw).

SPECS: Length: 4-3/4" (12.1cm) ir/kh  

BOX DIMENSIONS: 2.38" W. X .25" H. X 5.25" L. BOX WEIGHT: .01 LBS.