The strength or thickness of tape all depends on what is being shipped. For most packages under 30 lbs. the 1.9 polypropylene tape will work. If using PVC tape, start with the 2.2 standard grade. And 240 grade paper tape works incredibly well for heavy shipments. However, if you are shipping very heavy items or bulky items, having a thicker grade of tape might be helpful. Please reach out to us and we can help you figure out the best option. For more information read our blog