Hex size is measured across parallel flats. Inch keys meet ANSI specifications B18.3. All keys have a black-oxide finish except the metric high-visibility blue hex L-keys , which have an easy-to-identify corrosion-resistant blue coating.
This allen key is used for all set screws with 2.5mm size and for socket head cap screws 0-80UNF
Length: 1 3/4"
