Tested for us and highly approved by master letting artists. Allows you to loosen or tighten a screw to comfortablly accommodate any size nib including crowquills, Brause EF66 and large vintage nibs. Features a waterproof, wood/resin handle for decades of use. These holders are also available for left handed calligraphers. Please specify that you would like a left hand holder in the comments of your order form.