Because it is a belt clip type, you do not have to take the trouble to remove the belt from the belt loop at the time of installation and easy detachability. It is compact enough and so it fits well such as pen.
Even if it does not pass through the belt, you can purchase it for better use. As a comment on actually seeing the product, the metal clip is attached with a barb and it is not necessary to take it off during work. I think that it is more difficult to put out pockets than I thought. Personally I am sorry that I can not use it because I have metal allergy.