These stainless steel knife jacks measure a total of 20" in length with a 6" handle and 10" long blades. The blades taper down to approximately 4mm opening even the smallest of holes. The outside of the blades are rounded with flat insides. They have an extremely light spring for easy control. These jacks are excellent for opening cups, goblets, or any blown vessel. The back of the handle also works very well for a convenient paddle.