Seals and Buckles for Poly Strapping
Smooth, Open Seals:  Used for polypropylene strapping.  Seal is applied after strapping is tensioned.  Once applied it is closed with a crimping style sealer.  It is important that the seal and sealer are compatible, otherwise, there will be a low seal joint efficiency.

Serrated, Open Seals:  Used for polyester or polypropylene strapping.  Results in an improved seal joint efficiency when sealed with an appropriate crimping style sealer.  It is important that the seal and sealer are compatible, otherwise, there will be a low seal joint efficiency.
Steel Buckles: Strapping is laced through a steel buckle, then pulled by hand, or by means of a tensioner.  Steel buckles come in two styles:  one with the legs on opposite sides of the square opening, and one with an additional twist so that the legs are on the same side of the square opening.
Plastic Buckles: The legs of the plastic buckle are inserted through the loops of strapping, then pulled hand tight.  Plastic buckles are accepted by the US Postal Service for securing plastic strapping around letter trays that contain sorted bulk mail.
Magazine Seals: Specialty seals that are in a stack and are put into a certain combination strapping tools.  There are many sizes and shapes of magazine seals.  They are generally designed to operate in only one corresponding combination strapping tool.
 

Seals for Steel Strapping
Snap-On Seals:  Applied to steel strapping after tensioning.  This is the most common type of seal and used in conventional applications. 
Pusher Seals:  Used in pusher applications.  The seals are fully closed.  A pusher style tensioner pushes against the seal as the strapping is tensioned, so the seal becomes an integral part of the tensioning system.
Thread-On Seals:  Typically used in applications with heavier strapping.  The seal is pre-threaded onto the strap prior to tensioning.  As tensioning occurs, the seal helps keep the tensioned strapping aligned. 
Magazine Seals: Specialty seals that are in a stack and are put into a certain combination strapping tools.  There are many sizes and shapes of magazine seals.  They are generally designed to operate in only one corresponding combination strapping tool.  Magazine style steel strapping tools are becoming rare, and are being replaced with sealless strapping tools.