We grab the NRS 1. 5in Heavy-Duty Straps anytime we have to tie down anything on a trailer or our car rood. These polypropylene straps boast a tensile strength of 1500lb (tensile strength is the stress at which material breaks) and coated them with UV protectant. Two center-mounted stainless-steel springs in the buckles apply pressure evenly across the width of the strap for a secure hold.