CTI20 AeroConcept Carbon Inner Tube (12)

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Firenock AeroConcept Carbon Inner Tubes are made of high modulus carbon tube with 6 inches length. These tubes are specially made to integrate with Firenock AeroInsert-H inserts to form AeroConcept System. AeroConcept System can strengthen and stiffen the arrow (i.e. increase spine) especially the arrow front end without adding much weight to the entire arrow shaft. Moreover, precise weight adjustment of the entire arrow can be achieved by just adjusting the length of the carbon inner tube (i.e. a longer tube = greater weight and faster arrow straightness recovery or vice versa). It comes in 2 verisons: Heavy and light weight, 7.7 and 4.0gpi repectively.

CTI20L is the latest update to our carbon inner tube series.  It is a lightweight version of our classic CTI200 for 204 class arrows.  Our CTI20L has an outer diameter (OD) of 0.204” to 0.205” to snug fit into most 204 class arrows.  Due to the fact that the inner diameter (ID) of such arrows can be as small as 0202” and as large as 0.207” in extreme cases, it is crucial to double check that our carbon inner tubes can comfortably fit into every one of your arrows (even arrows from the same dozen can unfortunately have different IDs).  At Firenock, we recommend about 0.001” of a gap between the inner and outer tubes to allow space for two-part epoxy e.g. 0.206” ID main shaft requires a CTI with a 0.204” - 0.205” OD or 0.204” ID main shaft requires a CTI with a 0.202” - 0.203” OD.  While the first case shouldn’t need any DIY, the latter one will.  Reduce the OD of a carbon inner tube by installing it on a drill and sanding it down.  This process should be done slowly and carefully.  Make sure to sand the entire CTI evenly and periodically dry fit each into their designated arrows.  Finally, when you feel confident in your sizings, install with AGUSSE.


  • 12 pcs CTI of your choice
    • CTI200 Carbon Inner Tubes at ~7.7GPI or ~46gn for a 6" tube
    • CTI20L Carbon Inner Tubes at ~4.0GPI or ~24gn for a 6" tube


  • Clean arrow shaft with acetone before installation
  • Use slow set epoxy for installation (e.g. Firenock Epoxy AGUSSE)


  • 5

    Posted by Doug on Feb 20th 2021

    The science behind the Aeroconcept Carbon Inner Tube is absolutely ingenious. Doug