Nice piece of aluminum. However, the Dokk attaches to the writing half of the pen (good), but prevents the attachment of the upper extension of the pen (not good). In effect, it forces you to shorten the pen by half. This may not impair everyone's ability to hold the pen, but it makes it difficult for me to write because I need the full length of a pen to cradle between thumb and forefinger. If you are comfortable writing with stubs of pencils, then this will not bother you. On the other hand, what do you do with the top half while you are writing with the bottom half? Lose it? (Glad mine is orange.)
It is a convenient tool if your intended use of the pen is as an emergency/back-up writing tool (as opposed to something you will use to write in a journal while traveling) because you can secure it in your EDC bag or pack until you need it.