Polypropylene Smooth Metal Seals
The proper steel seals for polypropylene straps are smooth metal seals. A tensioner and the correct sealer with symmetrical jaws will produce tight professional seals.
Polyester Serrated Metal Seals
The proper metal seals for polyester straps are serrated metal seals. Look at the open seal in the picture below. If you look closely, you can see the rough texture fabricated inside the seal for better gripping power on slick surfaced polyester. A tensioner and the correct sealer with non—symmetrical jaws will produce tight professional seals. Be sure to place the long tooth of the sealer over the long open top of the seal (see arrows) before crimping.