| 2 springs | Tube Size | Tube Inner Diameter | 
  | SC-165 | 3/4” | 0.620” - 0.672” | 15.7 - 17.1mm | 
  | SC-170 | 20mm | 0.659” - 0.711” | 16.7 - 18.1mm | 
  | SC-200 | 7/8” | 0.745” - 0.797” | 18.9 - 20.2mm | 
  | SC-230 | 1” | 0.870” - 0.922” | 22.1 - 23.4mm | 
  | SC-280 | 30mm | 1.055” - 1.102” | 26.8 - 28.0mm | 
  | SC-290 | 1-1/4” | 1.118” - 1.173” | 28.4 - 29.8mm | 
  | SC-355 | 1-1/2” | 1.370” - 1.422” | 34.8 - 36.1mm | 
  | SC-480 | 2” | 1.870” - 1.921” | 47.5 - 48.8mm | 
 
 (1) All sizes can be done by 1/4-20 / 5/16-18 / M6 / M8 thread.
 (2) Only SC-480 is also done by 3/8-16 / M10 thread.