Pull tight security seals offer a tamper evident solution for sealing truck trailers, containers, airline food security boxes, postal service bags, ballot boxes, and various other cargo holds. Made of high-density polypropylene and a steel locking piece for extra hold these security plastic seals have a breaking strength of up to 35 lbs. and come laser etched with 7 digit sequential numbers. To use simply thread the end of the seal through the closure and into the area marked "enter" at the end of the seal and pull tight. Requires a cutting tool to remove.