SDI Heavy-Duty Staple Gun METAL MECHANISM which is durable and reliable tool for stapling needs. No stapling job is too difficult. The most daunting, complicated stapling projects are all in a day’s work with SDI Heavy Duty and Speciality Staplers. Heavy duty staplers power through 100+ sheets with ease and feature ergonomic handles to make the manual operation more comfortable. Specialty staplers make even the most unique stapling a stress-free experience with designs to meet specific needs such as industrial use or booklet fastening.