Precise Margin Control：Adjustable side and edge guides for precise document alignment, and customizable 3mm, 5mm, and 7mm margins for a professional look Humanized Punching Design：The full handle is sturdy and durable, and can be easily punched by both right and left hands, handling up to 12 sheets of 80 gsm paper at a time. Motorized coil inserter for different coil diameters, easy to operate, to meet different user habits and needs Economical and Practical：The binder comes with 50 Pcs 5/16'' black coils and a spiked starter kit with crimping pliers, making it an economical choice without the need to purchase additional coils. Suitable for school and small office environments, providing cost-effective binding solutions Multiple Size Adaptability：Tianse coil binders are compatible with Letter, A4 and A5 sizes, and the unique open-throat design allows for the insertion of large and non-standard pages to meet the needs of special projects. The mounting handle needs to be 90 degrees vertical to ensure precise operation and flexible response to a variety of binding tasks Efficient and Convenient Operation：Equipped with a motorized coil inserter for hands-free bookbinding, you can produce professional books quickly and easily, whether at home or in the office. The motorized coil inserter increases speed and handles a large number of jobs with ease. It is pre-lubricated and comes with oil-absorbent paper, making it easy to handle before use and saving time and effort › See more product details