which spring is related to 21-105

A professional from USA says:
I am looking to purchase your 21-105 . However all the springs you offer online are either too big or too small the 2 closest ones I was able to see is products 21-151 and 21-156 . If you could please offer some insight on which springs would fit best with this pin cap, that would greatly be appreciated.

Thank you in advance for your time.
A professional from USA says:
I have not seen any response to this question yet. Is someone working on it?

Is it possible for me to cut down the 21-126 to reduce the bottom OD to fit onto the 21-105 end cap, or will that reduce the necessary vertical tension?

Thank you.
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Paul from SWISCO responded:
The 21-105 nylon cap is meant to go with our 21-007 bi-fold door pin, which in turn uses the 21-251 barrel spring. Could this work for you?
A quick learner from philadelphia,Pa says:

I thought of that but I do not believe 21-251 barrel spring will fit over the throat of the 21-105 nylon cap.
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Paul from SWISCO responded:
Then you may have an entirely different setup. If you can, please show us some pictures of your original bifold pins and we will do our best to find something closer.
How to Install Bi-Fold Closet Door Pins
How to Install Bi-Fold Closet Door Pins
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