This is the Hard Chrome 4.0mm Turnbuckle Wrench from Muchmore Racing.
FEATURES: Hard chrome wrench with black handle Fits common 4mm turnbuckles made by Lunsford, HPI, Hot Bodies and many more
INCLUDES: One 4.0mm Chrome Turnbuckle Wrench
SPECS: Length: 77mm (3.03") Diameter of Handle: 7mm (0.28")
BOX DIMENSIONS: 2.50" W. X .25" H. X 3.25" L. BOX WEIGHT: .02 LBS.