I am very happy with the dedicated pen drilling jaws that I have. They are Teknatool Nova Pen Plus Jaws that I bought from WoodCraft that attach to a Teknatool Nova G3 chuck. They are extremely robust with plenty of surface area and length for gripping stock. They grip 1-inch square stock and 3/4-inch round and can be used to turn stock up to 9-10 inches long.
Although they are not the same design as the ones that have been mentioned in the post, they work very well when paired with the G3 chuck which comes with the additional benefit of being able to use other Nova accessory jaws for working with larger, non-pen projects.
Regards,
Dave