- Arrow ID
- Each arrow model (Victory RIP TKO for example) has a fixed inner diameter (ID) no matter what spine you order this refers to the inner diameter of your shaft. To determine this, remove your nock and use a set of calipers to measure the inner diameter.
- Arrow Nock Size
- This refers to the name of the nock size that your arrow uses. Most of the nocks nowadays have their letter marked on the nock itself.
- Max OD
- Each arrow model (Victory RIP TKO for example) has a fixed inner diameter (ID) no matter what spine you order. But the outer diameter (OD) changes depending on the spine. The Max OD spec tells you what the maximum outer diameter is that each FOB size can accomodate. So check the OD of your particular arrow spine to make sure that it will fit.
Steps To Choosing the Correct Size FOB:
- Determine what FOB size (Standard, H-Axis, X-axis, or Micro) your arrow falls under by either measuring its inner diameter of your shaft, or determining what nock size that your arrow uses.
- Measure the outer diameter (OD) of your arrow shaft and make sure that the measurement is less than the Max OD spec that the chart above shows for the FOB size your arrow falls under.
*** If you are unsure about what size arrow you have, please contact your arrow manufacturer or find your arrow manufacturer’s catalog below to look it up:
2019 Black Eagle Arrow Catalog (Spartan arrow uses X-nock, but not all spines fall under the Max OD requirements)