If you are among those allowed to order directly, it's likely the 3.5" for January.

Much like Goldilocks seeking the right (for her) bed, it is my primary EDC of the 3 XM sizes. I always pair it with a second XM. WHY? Because I like to carry 2 knives.

I carry the 3.5" Spanto Flipper with a 3" Slicer Flipper around the house and pair the 3.5 with a Spanto or Slicer XM-24 (4") Flipper whenever I head out into the world.

If you want a robust and dependable tool in your pocket, the XM certainly is a great contender.