FOR POLYESTER STRAPPING Specially designed inside treads grip polyester strapping. Highly recommended. Only compatible with 1/2" Uline Industrial Gripper Sealer , Uline Deluxe Gripper Sealer and Orgapack Combo Tool . ULINE offers over 38,500 boxes, plastic poly bags, mailing tubes, warehouse supplies and bubble wrap for your storage, packaging, or shipping supplies.