This is a .89x40mm Precision Hex Driver from Wiha.

FEATURES: Tapered ergonomic handle Rotating cap for precise turning and control with fingertip High alloy chrome-vanadium-molybdenum-steel blade Professional quality

INCLUDES: One .89x40mm Precision Hex Driver

SPECS: Shaft Length: 40mm (1.6") Total Length: 119mm (4.7") Tip Size: .89mm (0.035")  

BOX DIMENSIONS: .50" W. X .50" H. X 4.75" L. BOX WEIGHT: .03 LBS.