Ergonomic Breakdown: Human-Machine Interfaces
The cradle supports the index finger and fits large and small fingers well. It allows the weight of the hand to apply the downward pressure needed to mark. This removes the need to grip the pen to write, freeing up the fingers to simply direct the pen.
The cradle has the added benefit of "attaching" to your hand so dropping your pen will be a rare occurrence.
The pen body supports the "pencil" position you developed while learning to write. It has a cupped triangular surface that all three fingers register on easily. The grip is thick which reduces cramping and provides improved control and stability.
The clip is strong and provides a spring action to hold it securely.
The retractable cap is the only major flaw. It is not intuitive to use. You push the cap down to expose the pen tip and then push a button to cover it. That is opposite of what you would expect. However a few moments of playing with one, along with a few minor repairs, will educate you.
Ergonomic Breakdown: Comfort Factors
The cradle's rounded edges provide comfortable support for the index finger.
The cradle may irritate the skin between the index and middle finger. This skin is sensitive and usually not touched so it is prone to easy irritation. It may also cause discomfort if you wear a ring on the index or middle finger.
The cups of the triangular body form nicely to the fingertips.
Releasing your fingers from the need to grip removes the static stress on the fingers that normal writing causes thereby easing writer's cramp.
The cap mechanism has the possibility for accidental activation. It is quite possible that the pen will be compressed while in a pocket or bag in such a way that the marking surface is exposed.
Ergonomic Breakdown: Efficiency Factors
The pen is wider than normal, but it will not limit the places it can fit that much. It won't fit into the standard pen loop on a pad or satchel, but most pens with a large, ergonomic grip won't either. There is always the clip for these situations.
The form factor makes it easier to find in a purse, pocket or drawer full of pens.
Use, Misuse & Unknowns
A slight change in hand posture may occur that slants your writing differently.
Your normal writing strokes may be exaggerated until you realize that less motion is required to perform the same stroke.
You must move your wrist correctly. Lazy writing creep (scrunching up the fingers as you write) is not possible. You must move the wrist along the line as you write.
It may take a while to realize that you do not need to grip the pen hard. You do not need to grip the pen at all. You can let your thumb and fingers rest on the pen body lightly and simply fine tune the gross movements from the index fingers upper joint and the wrist.
The benefits for left handed writers are unknown. The body mechanics of a left handed writer are drastically different than a right hander. If there are any left handed readers interested in reviewing this product please contact me.