Pull tight security seals offer a tamper evident solution for sealing truck trailers, containers, airline security boxes, and various other cargo holds. Made of polyethylene these security plastic seals have a breaking strength of up to 39 lbs., have a metal locking device 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.