Key type air shaft is also called convex key air shaft, steel lug air shaft, lug type air shaft and etc, their working thoery is the same. 

This key type air shaft expanding part is its keys, normally one side expanded height can reached to 5mm or 6mm. For example, before expanding shaft's 

diameter is 74mm or 75mm, after expanding, shaft diameter can be reached to 79mm or 82mm. Special expanding height needed should be consult before placing order. As usually, 3 inch expanding lug type air shaft's steel tube outer diameter is 76mm. Its lugs are single keys, spread on the shaft body, balance stress, it is suitable to load heavy core and product.  

Strip type air shaft is also called strip type expanding shaft, strip plate air shaft, strip expandable air shaft, pneumatic strip shaft and etc, their working thoery is the same.

This strip type air shaft expanding part is the strip plates, its expanding height can be reached 4mm to 5mm. For example, before expanding, air shaft's diameter is 74 to 75mm, after expanding, its diameter can be reached 78mm to 79mm. Special expanding height needed should be consult before placing order. As usually, 3 inch expanding strip type air shaft's steel tube outer diameter is 76mm. Its stripd are single keys, spread on the shaft body, balance stress, it is suitable for high precision mechanical or light core or product.  

As usually, strip type air shaft is used for roller unwinding, roller rewinding is adopts key type air shaft. Key type air shaft load weight is heavier, strip type air shaft is used for rewinding, because its strip is in circle spread, it is less harm to paper core.