Traction gas spring functions by pulling the rod into the cylinder rather than extending. The natural position for this spring is compressed (rod-in-cylinder). 13mm ball and socket connectors are standard, but removable, leaving M10 threads on both sides. CeramPro -treated rod with powder-coated cylinder. This listing is for each. Adjustable Resistance : No Fitting Thread Size : M8 Fitting Type : Elbow Rod Thread Size : M8 Stroke : 7.87 Extended Length : 28.5 Compressed Length : 20.63 Type : Traction Material : Steel Cylinder Dia. : 0.87 Item : Gas Spring Rod Dia. : 0.32 Locking : No Force : 45 lb. Country of Origin (subject to change) : Germany