hex-key-dat

Internal hexagon

the specifications of Allen keys / hex keys are defined by the across-flats (AF) size, meaning the distance between two opposite flat sides of the hexagon.

So you can say:

  • “Hex key sizes are specified by the across-flats dimension.”
  • Example: a 6 mm Allen key means the hexagon measures 6 mm across the flats.

  • 1.5mm

  • 2mm
  • 2.5mm
  • 3mm
  • 4mm
  • 5mm
  • 6mm
  • 8mm
  • 10mm
  • 12mm
  • 14mm
  • 16mm
  • 17mm
  • 18mm
  • 19mm
  • 20mm

ref